[U-Boot] [PATCH] gpt: add part-uuid and part-num subcommands
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com --- cmd/gpt.c | 67 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ doc/README.gpt | 21 ++++++++++++++++++ 2 files changed, 88 insertions(+)
diff --git a/cmd/gpt.c b/cmd/gpt.c index 707d861766..bef292230e 100644 --- a/cmd/gpt.c +++ b/cmd/gpt.c @@ -355,6 +355,64 @@ static int do_get_gpt_info(struct blk_desc *dev_desc) } return ret; } + +static struct disk_part *find_part_by_label(const char *label) +{ + struct disk_part *part = NULL; + struct disk_part *curr; + + list_for_each_entry(curr, &disk_partitions, list) { + /* Check for the first match of the label we're looking + * for against the partition label */ + if (!strcmp((const char*)curr->gpt_part_info.name, + label)) { + part = curr; + break; + } + } + + return part; +} + +/* Find a partition UUID by label and save that UUID to the environment + * variable specified */ +static int do_get_part_uuid(struct blk_desc *dev_desc, const char *label, + const char *namestr) +{ + int ret; + + ret = get_gpt_info(dev_desc); + if (ret > 0) { + struct disk_part *part = find_part_by_label(label); + if (part) { + env_set(namestr, part->gpt_part_info.uuid); + ret = 0; + } + + del_gpt_info(); + } + + return ret; +} + +/* Find a partition number by label and save that number to the environment + * variable specified */ +static int do_get_part_num(struct blk_desc *dev_desc, const char *label, + const char *namestr) +{ + int ret = get_gpt_info(dev_desc); + if (ret > 0) { + struct disk_part *part = find_part_by_label(label); + if (part) { + env_set_ulong(namestr, part->partnum); + ret = 0; + } + + del_gpt_info(); + } + + return ret; +} #endif
/** @@ -851,6 +909,10 @@ static int do_gpt(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) #ifdef CONFIG_CMD_GPT_RENAME } else if (strcmp(argv[1], "read") == 0) { ret = do_get_gpt_info(blk_dev_desc); + } else if (strcmp(argv[1], "part-uuid") == 0 && argc == 6) { + ret = do_get_part_uuid(blk_dev_desc, argv[4], argv[5]); + } else if (strcmp(argv[1], "part-num") == 0 && argc == 6) { + ret = do_get_part_num(blk_dev_desc, argv[4], argv[5]); } else if ((strcmp(argv[1], "swap") == 0) || (strcmp(argv[1], "rename") == 0)) { ret = do_rename_gpt_parts(blk_dev_desc, argv[1], argv[4], argv[5]); @@ -887,6 +949,11 @@ U_BOOT_CMD(gpt, CONFIG_SYS_MAXARGS, 1, do_gpt, " gpt guid mmc 0\n" " gpt guid mmc 0 varname\n" #ifdef CONFIG_CMD_GPT_RENAME + "gpt partition label commands:\n" + "gpt part-uuid <interface> <dev> <label> <varname>\n" + " - set environment variable to UUID of label\n" + "gpt part-num <interface> <dev> <label> <varname>\n" + " - set environment variable to partition number of label\n" "gpt partition renaming commands:\n" "gpt swap <interface> <dev> <name1> <name2>\n" " - change all partitions named name1 to name2\n" diff --git a/doc/README.gpt b/doc/README.gpt index d3db8bce1c..edb99b6c68 100644 --- a/doc/README.gpt +++ b/doc/README.gpt @@ -275,6 +275,27 @@ Some strings can be also used at the place of known GUID :
They are also used to display the type of partition in "part list" command.
+Identifying Partitions in U-Boot: +================================= + +Two subcommands may be used to identify partitions by their label. This can be +useful for determining which partition to use or for setting boot arguments. +The 'gpt part-uuid' command looks up a partition UUID for a given label and +stores it in an environment variable. The 'gpt part-num' command looks up a +partition number for a given label and stores it in an environment variable. +The first partition with a matching label is used. + +For example, to find the UUID of a partition named 'rootfs0' and then use it +for boot arguments: + +U-BOOT> gpt part-uuid mmc 0 rootfs0 rootfsuuid +U-BOOT> setenv bootargs root=PARTUUID=${rootfsuuid} + +Or, for example, to find the partition number for a partition named 'kernel' +and load a file from it: + +U-BOOT> gpt part-num mmc 0 kernel kernelnum +U-BOOT> fatload mmc 0:${kernelnum} ${loadaddr} zImage
Useful info: ============
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote:
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
Hi Otavio,
On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador otavio.salvador@ossystems.com.br wrote:
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote:
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
Sorry, I missed the part cmd, it doesn't seem to be documented in doc/ and it's unclear what <dev> means there. I'll investigate and see if I can use it for what I'm trying to do, it looks like it should work.
Hi Andrey,
Hi Otavio,
On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador otavio.salvador@ossystems.com.br wrote:
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote:
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
Sorry, I missed the part cmd, it doesn't seem to be documented in doc/ and it's unclear what <dev> means there.
If I may ask - Andrey, if you are now on this "topic" - would you dare to add some ./doc entry for 'part' command?
I'll investigate and see if I can use it for what I'm trying to do, it looks like it should work. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Otavio,
On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador otavio.salvador@ossystems.com.br wrote:
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote:
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
Sorry, I missed the part cmd, it doesn't seem to be documented in doc/ and it's unclear what <dev> means there.
If I may ask - Andrey, if you are now on this "topic" - would you dare to add some ./doc entry for 'part' command?
Yes, I will do that.
On Thu, 9 Nov 2017 07:34:44 -0800 Andrey Yurovsky yurovsky@gmail.com wrote:
On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Otavio,
On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador otavio.salvador@ossystems.com.br wrote:
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote:
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
Sorry, I missed the part cmd, it doesn't seem to be documented in doc/ and it's unclear what <dev> means there.
If I may ask - Andrey, if you are now on this "topic" - would you dare to add some ./doc entry for 'part' command?
Yes, I will do that.
Thanks :-)
Hi Lukasz,
On Thu, Nov 9, 2017 at 2:28 PM, Lukasz Majewski l.majewski@majess.pl wrote:
On Thu, 9 Nov 2017 07:34:44 -0800 Andrey Yurovsky yurovsky@gmail.com wrote:
On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Otavio,
On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador otavio.salvador@ossystems.com.br wrote:
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote:
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
Sorry, I missed the part cmd, it doesn't seem to be documented in doc/ and it's unclear what <dev> means there.
If I may ask - Andrey, if you are now on this "topic" - would you dare to add some ./doc entry for 'part' command?
Yes, I will do that.
Thanks :-)
On further investigation I am not sure that it's possible to extend the part command to retrieve UUIDs by label because of the design of the partition type drivers. Here is how I understand it to work: 1. the "part" command uses part_get_info() and in turn gets a partition driver and can call print() there (which is how EFI/GPT disks are printed with "part list"). The right information (including label) is printed but it's not tied to the caller in any way. 2. "part uuid" blk_get_device_part_str() which in turn can get information but referenced by partition number (and only partition number, due to how part_get_info() works). There's nothing at the 'part' layer tying a label to a number though so one would already need to know the number, which is the problem I'm trying to solve.
This layering keeps partitioning generalized and decoupled from the underlying partition "driver" but there's no concept of a label in the "driver" API. I'm not sure if it's reasonable to extend it since part_get_info() and similar really don't have a way to map labels at this layer so perhaps extending the GPT-specific command is the only reasonable approach?
Hi Andrey,
Hi Lukasz,
On Thu, Nov 9, 2017 at 2:28 PM, Lukasz Majewski l.majewski@majess.pl wrote:
On Thu, 9 Nov 2017 07:34:44 -0800 Andrey Yurovsky yurovsky@gmail.com wrote:
On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Otavio,
On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador otavio.salvador@ossystems.com.br wrote:
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote: > From: Andrey Yurovsky yurovsky@gmail.com > > It is useful to be able to retrieve a partition UUID or > number given the partition label, for instance some systems > use the partition label to indicate the purpose of the > partition (such as "rootfs0" being the 0th root file system > in an A/B image scheme). > > Add "gpt part-uuid" to retrieve the partition UUID for a > given label and "gpt part-num" to retrieve the partition > number for a given label along with some documentation. > > Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
Sorry, I missed the part cmd, it doesn't seem to be documented in doc/ and it's unclear what <dev> means there.
If I may ask - Andrey, if you are now on this "topic" - would you dare to add some ./doc entry for 'part' command?
Yes, I will do that.
Thanks :-)
On further investigation I am not sure that it's possible to extend the part command to retrieve UUIDs by label because of the design of the partition type drivers. Here is how I understand it to work:
- the "part" command uses part_get_info() and in turn gets a
partition driver and can call print() there (which is how EFI/GPT disks are printed with "part list"). The right information (including label) is printed but it's not tied to the caller in any way.
Maybe you can set some env variable with proper data?
For example, please refer to ./cmd/part.c do_part_start() function.
Example call from envs (include/configs/display5.h): "part start mmc ${mmcdev} ${kernel_part} lba_start; " \
- "part uuid" blk_get_device_part_str() which in turn can get
information but referenced by partition number (and only partition number, due to how part_get_info() works). There's nothing at the 'part' layer tying a label to a number though so one would already need to know the number, which is the problem I'm trying to solve.
This layering keeps partitioning generalized and decoupled from the underlying partition "driver" but there's no concept of a label in the "driver" API. I'm not sure if it's reasonable to extend it since part_get_info() and similar really don't have a way to map labels at this layer so perhaps extending the GPT-specific command is the only reasonable approach? _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
Hi Lukasz,
On Tue, Nov 14, 2017 at 1:45 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Thu, Nov 9, 2017 at 2:28 PM, Lukasz Majewski l.majewski@majess.pl wrote:
On Thu, 9 Nov 2017 07:34:44 -0800 Andrey Yurovsky yurovsky@gmail.com wrote:
On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Otavio,
On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador otavio.salvador@ossystems.com.br wrote: > On Tue, Nov 7, 2017 at 10:43 PM, your name > yurovsky@gmail.com wrote: >> From: Andrey Yurovsky yurovsky@gmail.com >> >> It is useful to be able to retrieve a partition UUID or >> number given the partition label, for instance some systems >> use the partition label to indicate the purpose of the >> partition (such as "rootfs0" being the 0th root file system >> in an A/B image scheme). >> >> Add "gpt part-uuid" to retrieve the partition UUID for a >> given label and "gpt part-num" to retrieve the partition >> number for a given label along with some documentation. >> >> Signed-off-by: Andrey Yurovsky yurovsky@gmail.com > > Why not use the 'part' cmd? it provides it.
Sorry, I missed the part cmd, it doesn't seem to be documented in doc/ and it's unclear what <dev> means there.
If I may ask - Andrey, if you are now on this "topic" - would you dare to add some ./doc entry for 'part' command?
Yes, I will do that.
Thanks :-)
On further investigation I am not sure that it's possible to extend the part command to retrieve UUIDs by label because of the design of the partition type drivers. Here is how I understand it to work:
- the "part" command uses part_get_info() and in turn gets a
partition driver and can call print() there (which is how EFI/GPT disks are printed with "part list"). The right information (including label) is printed but it's not tied to the caller in any way.
Maybe you can set some env variable with proper data?
For example, please refer to ./cmd/part.c do_part_start() function.
Example call from envs (include/configs/display5.h): "part start mmc ${mmcdev} ${kernel_part} lba_start; " \
Again that assumes the partition is referred to by number, I need it to be by label, and the part/disk interface does not seem to have any way to utilize labels. Unfortunately it looks like my original approach with the gpt command is the only way to implement this with the current design (at least from what I see here). Please let me know if I've missed something. Thanks!
Hi Andrey,
Hi Lukasz,
On Tue, Nov 14, 2017 at 1:45 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Thu, Nov 9, 2017 at 2:28 PM, Lukasz Majewski l.majewski@majess.pl wrote:
On Thu, 9 Nov 2017 07:34:44 -0800 Andrey Yurovsky yurovsky@gmail.com wrote:
On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
> Hi Otavio, > > On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador > otavio.salvador@ossystems.com.br wrote: > > On Tue, Nov 7, 2017 at 10:43 PM, your name > > yurovsky@gmail.com wrote: > >> From: Andrey Yurovsky yurovsky@gmail.com > >> > >> It is useful to be able to retrieve a partition UUID or > >> number given the partition label, for instance some > >> systems use the partition label to indicate the purpose > >> of the partition (such as "rootfs0" being the 0th root > >> file system in an A/B image scheme). > >> > >> Add "gpt part-uuid" to retrieve the partition UUID for a > >> given label and "gpt part-num" to retrieve the partition > >> number for a given label along with some documentation. > >> > >> Signed-off-by: Andrey Yurovsky yurovsky@gmail.com > > > > Why not use the 'part' cmd? it provides it. > > Sorry, I missed the part cmd, it doesn't seem to be > documented in doc/ and it's unclear what <dev> means there.
If I may ask - Andrey, if you are now on this "topic" - would you dare to add some ./doc entry for 'part' command?
Yes, I will do that.
Thanks :-)
On further investigation I am not sure that it's possible to extend the part command to retrieve UUIDs by label because of the design of the partition type drivers. Here is how I understand it to work:
- the "part" command uses part_get_info() and in turn gets a
partition driver and can call print() there (which is how EFI/GPT disks are printed with "part list"). The right information (including label) is printed but it's not tied to the caller in any way.
Maybe you can set some env variable with proper data?
For example, please refer to ./cmd/part.c do_part_start() function.
Example call from envs (include/configs/display5.h): "part start mmc ${mmcdev} ${kernel_part} lba_start; " \
Again that assumes the partition is referred to by number, I need it to be by label, and the part/disk interface does not seem to have any way to utilize labels. Unfortunately it looks like my original approach with the gpt command is the only way to implement this with the current design (at least from what I see here). Please let me know if I've missed something. Thanks!
Please correct me if I'm wrong - you need the starting LBA of the partition named e.g. "FOO" in gpt ?
Conceptually it would be correct to have:
part start <interface> <dev> <NAME - e.g.'FOO'> <env to set> gpt start <interface> <dev> <NAME- e.g. 'FOO'> <env to set>
If your code is really _small_ and can be used only with GPT, then lets go for the second option.
On Mon, Dec 4, 2017 at 1:12 PM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Tue, Nov 14, 2017 at 1:45 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Thu, Nov 9, 2017 at 2:28 PM, Lukasz Majewski l.majewski@majess.pl wrote:
On Thu, 9 Nov 2017 07:34:44 -0800 Andrey Yurovsky yurovsky@gmail.com wrote:
On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski l.majewski@majess.pl wrote: > Hi Andrey, > >> Hi Otavio, >> >> On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador >> otavio.salvador@ossystems.com.br wrote: >> > On Tue, Nov 7, 2017 at 10:43 PM, your name >> > yurovsky@gmail.com wrote: >> >> From: Andrey Yurovsky yurovsky@gmail.com >> >> >> >> It is useful to be able to retrieve a partition UUID or >> >> number given the partition label, for instance some >> >> systems use the partition label to indicate the purpose >> >> of the partition (such as "rootfs0" being the 0th root >> >> file system in an A/B image scheme). >> >> >> >> Add "gpt part-uuid" to retrieve the partition UUID for a >> >> given label and "gpt part-num" to retrieve the partition >> >> number for a given label along with some documentation. >> >> >> >> Signed-off-by: Andrey Yurovsky yurovsky@gmail.com >> > >> > Why not use the 'part' cmd? it provides it. >> >> Sorry, I missed the part cmd, it doesn't seem to be >> documented in doc/ and it's unclear what <dev> means there. > > If I may ask - Andrey, if you are now on this "topic" - would > you dare to add some ./doc entry for 'part' command?
Yes, I will do that.
Thanks :-)
On further investigation I am not sure that it's possible to extend the part command to retrieve UUIDs by label because of the design of the partition type drivers. Here is how I understand it to work:
- the "part" command uses part_get_info() and in turn gets a
partition driver and can call print() there (which is how EFI/GPT disks are printed with "part list"). The right information (including label) is printed but it's not tied to the caller in any way.
Maybe you can set some env variable with proper data?
For example, please refer to ./cmd/part.c do_part_start() function.
Example call from envs (include/configs/display5.h): "part start mmc ${mmcdev} ${kernel_part} lba_start; " \
Again that assumes the partition is referred to by number, I need it to be by label, and the part/disk interface does not seem to have any way to utilize labels. Unfortunately it looks like my original approach with the gpt command is the only way to implement this with the current design (at least from what I see here). Please let me know if I've missed something. Thanks!
Please correct me if I'm wrong - you need the starting LBA of the partition named e.g. "FOO" in gpt ?
Conceptually it would be correct to have:
part start <interface> <dev> <NAME - e.g.'FOO'> <env to set> gpt start <interface> <dev> <NAME- e.g. 'FOO'> <env to set>
If your code is really _small_ and can be used only with GPT, then lets go for the second option.
The use cases I have in mind:
1. determine which root file system to use by label, let's say "rootfs1" and pass its UUID to the Linux kernel via the command line, ex: "PART-UUID=${uuid}". To do this we need a way to ask for a UUID corresponding to a label in the partition table (given duplicate labels, assume it gives us the first or last match). 2. determine which file system to load a file from (ex: fatload) given a label. I'm not sure that the starting LBA is helpful here, we really are looking to map a label to a partition number in the table.
The implementation of "part start" interprets the argument as a partition number, so I can get the stating LBA if I know the partition number but I don't see a way (via cmd/disk.c) to get anything useful if all I know is a label, and that is what I'm trying to solve.
Hi Andrey,
On Mon, Dec 4, 2017 at 1:12 PM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Tue, Nov 14, 2017 at 1:45 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Thu, Nov 9, 2017 at 2:28 PM, Lukasz Majewski l.majewski@majess.pl wrote:
On Thu, 9 Nov 2017 07:34:44 -0800 Andrey Yurovsky yurovsky@gmail.com wrote:
> On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski > l.majewski@majess.pl wrote: > > Hi Andrey, > > > >> Hi Otavio, > >> > >> On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador > >> otavio.salvador@ossystems.com.br wrote: > >> > On Tue, Nov 7, 2017 at 10:43 PM, your name > >> > yurovsky@gmail.com wrote: > >> >> From: Andrey Yurovsky yurovsky@gmail.com > >> >> > >> >> It is useful to be able to retrieve a partition UUID or > >> >> number given the partition label, for instance some > >> >> systems use the partition label to indicate the purpose > >> >> of the partition (such as "rootfs0" being the 0th root > >> >> file system in an A/B image scheme). > >> >> > >> >> Add "gpt part-uuid" to retrieve the partition UUID for > >> >> a given label and "gpt part-num" to retrieve the > >> >> partition number for a given label along with some > >> >> documentation. > >> >> > >> >> Signed-off-by: Andrey Yurovsky yurovsky@gmail.com > >> > > >> > Why not use the 'part' cmd? it provides it. > >> > >> Sorry, I missed the part cmd, it doesn't seem to be > >> documented in doc/ and it's unclear what <dev> means > >> there. > > > > If I may ask - Andrey, if you are now on this "topic" - > > would you dare to add some ./doc entry for 'part' > > command? > > Yes, I will do that.
Thanks :-)
On further investigation I am not sure that it's possible to extend the part command to retrieve UUIDs by label because of the design of the partition type drivers. Here is how I understand it to work: 1. the "part" command uses part_get_info() and in turn gets a partition driver and can call print() there (which is how EFI/GPT disks are printed with "part list"). The right information (including label) is printed but it's not tied to the caller in any way.
Maybe you can set some env variable with proper data?
For example, please refer to ./cmd/part.c do_part_start() function.
Example call from envs (include/configs/display5.h): "part start mmc ${mmcdev} ${kernel_part} lba_start; " \
Again that assumes the partition is referred to by number, I need it to be by label, and the part/disk interface does not seem to have any way to utilize labels. Unfortunately it looks like my original approach with the gpt command is the only way to implement this with the current design (at least from what I see here). Please let me know if I've missed something. Thanks!
Please correct me if I'm wrong - you need the starting LBA of the partition named e.g. "FOO" in gpt ?
Conceptually it would be correct to have:
part start <interface> <dev> <NAME - e.g.'FOO'> <env to set> gpt start <interface> <dev> <NAME- e.g. 'FOO'> <env to set>
If your code is really _small_ and can be used only with GPT, then lets go for the second option.
The use cases I have in mind:
- determine which root file system to use by label, let's say
"rootfs1" and pass its UUID to the Linux kernel via the command line, ex: "PART-UUID=${uuid}". To do this we need a way to ask for a UUID corresponding to a label in the partition table (given duplicate labels, assume it gives us the first or last match).
I see. I thought that you need start LBA.
From your use case it seems like extending the 'gpt' command is the right thing to do - since already some uuid handling is done there.
- determine which file system to load a file from (ex: fatload) given
a label.
There is a group of generic commands - like load, ls, etc.
I'm not sure that the starting LBA is helpful here, we really are looking to map a label to a partition number in the table.
If you are using GPT, then you also may want to extend the 'gpt' command -> iterate through PTEs and when label matched, return the part number. With it you can use e.g. load mmc 0 <part> file.
The implementation of "part start" interprets the argument as a partition number, so I can get the stating LBA if I know the partition number but I don't see a way (via cmd/disk.c) to get anything useful if all I know is a label, and that is what I'm trying to solve.
On Tue, Dec 5, 2017 at 7:10 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
On Mon, Dec 4, 2017 at 1:12 PM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Tue, Nov 14, 2017 at 1:45 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Thu, Nov 9, 2017 at 2:28 PM, Lukasz Majewski l.majewski@majess.pl wrote: > On Thu, 9 Nov 2017 07:34:44 -0800 > Andrey Yurovsky yurovsky@gmail.com wrote: > >> On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski >> l.majewski@majess.pl wrote: >> > Hi Andrey, >> > >> >> Hi Otavio, >> >> >> >> On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador >> >> otavio.salvador@ossystems.com.br wrote: >> >> > On Tue, Nov 7, 2017 at 10:43 PM, your name >> >> > yurovsky@gmail.com wrote: >> >> >> From: Andrey Yurovsky yurovsky@gmail.com >> >> >> >> >> >> It is useful to be able to retrieve a partition UUID or >> >> >> number given the partition label, for instance some >> >> >> systems use the partition label to indicate the purpose >> >> >> of the partition (such as "rootfs0" being the 0th root >> >> >> file system in an A/B image scheme). >> >> >> >> >> >> Add "gpt part-uuid" to retrieve the partition UUID for >> >> >> a given label and "gpt part-num" to retrieve the >> >> >> partition number for a given label along with some >> >> >> documentation. >> >> >> >> >> >> Signed-off-by: Andrey Yurovsky yurovsky@gmail.com >> >> > >> >> > Why not use the 'part' cmd? it provides it. >> >> >> >> Sorry, I missed the part cmd, it doesn't seem to be >> >> documented in doc/ and it's unclear what <dev> means >> >> there. >> > >> > If I may ask - Andrey, if you are now on this "topic" - >> > would you dare to add some ./doc entry for 'part' >> > command? >> >> Yes, I will do that. > > Thanks :-)
On further investigation I am not sure that it's possible to extend the part command to retrieve UUIDs by label because of the design of the partition type drivers. Here is how I understand it to work: 1. the "part" command uses part_get_info() and in turn gets a partition driver and can call print() there (which is how EFI/GPT disks are printed with "part list"). The right information (including label) is printed but it's not tied to the caller in any way.
Maybe you can set some env variable with proper data?
For example, please refer to ./cmd/part.c do_part_start() function.
Example call from envs (include/configs/display5.h): "part start mmc ${mmcdev} ${kernel_part} lba_start; " \
Again that assumes the partition is referred to by number, I need it to be by label, and the part/disk interface does not seem to have any way to utilize labels. Unfortunately it looks like my original approach with the gpt command is the only way to implement this with the current design (at least from what I see here). Please let me know if I've missed something. Thanks!
Please correct me if I'm wrong - you need the starting LBA of the partition named e.g. "FOO" in gpt ?
Conceptually it would be correct to have:
part start <interface> <dev> <NAME - e.g.'FOO'> <env to set> gpt start <interface> <dev> <NAME- e.g. 'FOO'> <env to set>
If your code is really _small_ and can be used only with GPT, then lets go for the second option.
The use cases I have in mind:
- determine which root file system to use by label, let's say
"rootfs1" and pass its UUID to the Linux kernel via the command line, ex: "PART-UUID=${uuid}". To do this we need a way to ask for a UUID corresponding to a label in the partition table (given duplicate labels, assume it gives us the first or last match).
I see. I thought that you need start LBA.
From your use case it seems like extending the 'gpt' command is the right thing to do - since already some uuid handling is done there.
In that case would you please let me know if the patch I sent is reasonable?
- determine which file system to load a file from (ex: fatload) given
a label.
There is a group of generic commands - like load, ls, etc.
It seems that the lowest common denominator for these is indeed the partition number (then they can talk to the disk driver) so adding a way to map labels to that number (as in my original patch) may be useful, the user's script can then use these commands once it learns that information via the gpt command.
I'm not sure that the starting LBA is helpful here, we really are looking to map a label to a partition number in the table.
If you are using GPT, then you also may want to extend the 'gpt' command -> iterate through PTEs and when label matched, return the part number. With it you can use e.g. load mmc 0 <part> file.
Right, exactly. For that I added "gpt part-num" in the patch.
The implementation of "part start" interprets the argument as a partition number, so I can get the stating LBA if I know the partition number but I don't see a way (via cmd/disk.c) to get anything useful if all I know is a label, and that is what I'm trying to solve.
-- Best regards,
Łukasz Majewski
Hi Andrey,
Please resent it to u-boot ML.
On Tue, Dec 5, 2017 at 7:10 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
On Mon, Dec 4, 2017 at 1:12 PM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
Hi Lukasz,
On Tue, Nov 14, 2017 at 1:45 AM, Lukasz Majewski l.majewski@majess.pl wrote:
Hi Andrey,
> Hi Lukasz, > > On Thu, Nov 9, 2017 at 2:28 PM, Lukasz Majewski > l.majewski@majess.pl wrote: > > On Thu, 9 Nov 2017 07:34:44 -0800 > > Andrey Yurovsky yurovsky@gmail.com wrote: > > > >> On Thu, Nov 9, 2017 at 1:55 AM, Lukasz Majewski > >> l.majewski@majess.pl wrote: > >> > Hi Andrey, > >> > > >> >> Hi Otavio, > >> >> > >> >> On Wed, Nov 8, 2017 at 2:47 AM, Otavio Salvador > >> >> otavio.salvador@ossystems.com.br wrote: > >> >> > On Tue, Nov 7, 2017 at 10:43 PM, your name > >> >> > yurovsky@gmail.com wrote: > >> >> >> From: Andrey Yurovsky yurovsky@gmail.com > >> >> >> > >> >> >> It is useful to be able to retrieve a partition > >> >> >> UUID or number given the partition label, for > >> >> >> instance some systems use the partition label to > >> >> >> indicate the purpose of the partition (such as > >> >> >> "rootfs0" being the 0th root file system in an A/B > >> >> >> image scheme). > >> >> >> > >> >> >> Add "gpt part-uuid" to retrieve the partition UUID > >> >> >> for a given label and "gpt part-num" to retrieve the > >> >> >> partition number for a given label along with some > >> >> >> documentation. > >> >> >> > >> >> >> Signed-off-by: Andrey Yurovsky > >> >> >> yurovsky@gmail.com > >> >> > > >> >> > Why not use the 'part' cmd? it provides it. > >> >> > >> >> Sorry, I missed the part cmd, it doesn't seem to be > >> >> documented in doc/ and it's unclear what <dev> means > >> >> there. > >> > > >> > If I may ask - Andrey, if you are now on this "topic" - > >> > would you dare to add some ./doc entry for 'part' > >> > command? > >> > >> Yes, I will do that. > > > > Thanks :-) > > On further investigation I am not sure that it's possible to > extend the part command to retrieve UUIDs by label because of > the design of the partition type drivers. Here is how I > understand it to work: 1. the "part" command uses > part_get_info() and in turn gets a partition driver and can > call print() there (which is how EFI/GPT disks are printed > with "part list"). The right information (including label) is > printed but it's not tied to the caller in any way.
Maybe you can set some env variable with proper data?
For example, please refer to ./cmd/part.c do_part_start() function.
Example call from envs (include/configs/display5.h): "part start mmc ${mmcdev} ${kernel_part} lba_start; " \
Again that assumes the partition is referred to by number, I need it to be by label, and the part/disk interface does not seem to have any way to utilize labels. Unfortunately it looks like my original approach with the gpt command is the only way to implement this with the current design (at least from what I see here). Please let me know if I've missed something. Thanks!
Please correct me if I'm wrong - you need the starting LBA of the partition named e.g. "FOO" in gpt ?
Conceptually it would be correct to have:
part start <interface> <dev> <NAME - e.g.'FOO'> <env to set> gpt start <interface> <dev> <NAME- e.g. 'FOO'> <env to set>
If your code is really _small_ and can be used only with GPT, then lets go for the second option.
The use cases I have in mind:
- determine which root file system to use by label, let's say
"rootfs1" and pass its UUID to the Linux kernel via the command line, ex: "PART-UUID=${uuid}". To do this we need a way to ask for a UUID corresponding to a label in the partition table (given duplicate labels, assume it gives us the first or last match).
I see. I thought that you need start LBA.
From your use case it seems like extending the 'gpt' command is the right thing to do - since already some uuid handling is done there.
In that case would you please let me know if the patch I sent is reasonable?
- determine which file system to load a file from (ex: fatload)
given a label.
There is a group of generic commands - like load, ls, etc.
It seems that the lowest common denominator for these is indeed the partition number (then they can talk to the disk driver) so adding a way to map labels to that number (as in my original patch) may be useful, the user's script can then use these commands once it learns that information via the gpt command.
I'm not sure that the starting LBA is helpful here, we really are looking to map a label to a partition number in the table.
If you are using GPT, then you also may want to extend the 'gpt' command -> iterate through PTEs and when label matched, return the part number. With it you can use e.g. load mmc 0 <part> file.
Right, exactly. For that I added "gpt part-num" in the patch.
The implementation of "part start" interprets the argument as a partition number, so I can get the stating LBA if I know the partition number but I don't see a way (via cmd/disk.c) to get anything useful if all I know is a label, and that is what I'm trying to solve.
-- Best regards,
Łukasz Majewski
On Wed, Nov 8, 2017 at 2:47 AM Otavio Salvador < otavio.salvador@ossystems.com.br> wrote:
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote:
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
The use case is, given a label, find the UUID and/or the partition number. I see that 'part' can give me the UUID if I knew the partition number, it can print the whole table (but I don't think I can use that output cleanly), and it can list the partition numbers. I don't think I can solve my problem with 'part' as-is unless I have missed something.
If that's the case would it be alright to add these subcommands to 'part'? Thank you again,
-Andrey
On Wed, Nov 8, 2017 at 3:16 PM, Andrey Yurovsky yurovsky@gmail.com wrote:
On Wed, Nov 8, 2017 at 2:47 AM Otavio Salvador otavio.salvador@ossystems.com.br wrote:
On Tue, Nov 7, 2017 at 10:43 PM, your name yurovsky@gmail.com wrote:
From: Andrey Yurovsky yurovsky@gmail.com
It is useful to be able to retrieve a partition UUID or number given the partition label, for instance some systems use the partition label to indicate the purpose of the partition (such as "rootfs0" being the 0th root file system in an A/B image scheme).
Add "gpt part-uuid" to retrieve the partition UUID for a given label and "gpt part-num" to retrieve the partition number for a given label along with some documentation.
Signed-off-by: Andrey Yurovsky yurovsky@gmail.com
Why not use the 'part' cmd? it provides it.
The use case is, given a label, find the UUID and/or the partition number. I see that 'part' can give me the UUID if I knew the partition number, it can print the whole table (but I don't think I can use that output cleanly), and it can list the partition numbers. I don't think I can solve my problem with 'part' as-is unless I have missed something.
If that's the case would it be alright to add these subcommands to 'part'? Thank you again,
It looks to be the best approach for me.
participants (4)
-
Andrey Yurovsky -
Lukasz Majewski -
Otavio Salvador -
your name