On 5/14/24 14:58, Mark Kettenis wrote:
Date: Tue, 14 May 2024 14:49:47 +0200 From: Heinrich Schuchardt heinrich.schuchardt@canonical.com
Hi Heinrich,
On 4/26/24 17:47, Ilias Apalodimas wrote:
Hi Heinrich
On Fri, 26 Apr 2024 at 17:53, Heinrich Schuchardt heinrich.schuchardt@canonical.com wrote:
On 26.04.24 16:30, Ilias Apalodimas wrote:
Hi Heinrich,
On Fri, 26 Apr 2024 at 17:13, Heinrich Schuchardt heinrich.schuchardt@canonical.com wrote:
Provide a function to append a device_path to a list of device paths that is separated by final end nodes.
Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com
include/efi_loader.h | 3 +++ lib/efi_loader/efi_device_path.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+)diff --git a/include/efi_loader.h b/include/efi_loader.h index 9600941aa32..a7d7b8324f1 100644 --- a/include/efi_loader.h +++ b/include/efi_loader.h @@ -944,6 +944,9 @@ struct efi_load_option {
struct efi_device_path *efi_dp_from_lo(struct efi_load_option *lo, const efi_guid_t *guid);+struct efi_device_path *efi_dp_merge(const struct efi_device_path *dp1,
efi_uintn_t *size,const struct efi_device_path *dp2);diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c index 46aa59b9e40..16cbe41d32f 100644 --- a/lib/efi_loader/efi_device_path.c +++ b/lib/efi_loader/efi_device_path.c @@ -270,6 +270,37 @@ struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp) return ndp; }
+/**
- efi_dp_merge() - Concatenate two device paths separated by final end node
- @dp1: first device path
- @size: pointer to length of @dp1, total size on return
- @dp2: second device path
- Return: concatenated device path or NULL
- */
+struct efi_device_path *efi_dp_merge(const struct efi_device_path *dp1,
efi_uintn_t *size,const struct efi_device_path *dp2)+{
efi_uintn_t len, len1, len2;struct efi_device_path *dp;u8 *p;len1 = *size;len2 = efi_dp_size(dp2) + sizeof(END);len = len1 + len2;dp = efi_alloc(len);if (!dp)return NULL;memcpy(dp, dp1, len1);p = (u8 *)dp + len1;memcpy(p, dp2, len2);*size = len;Can't we just use efi_dp_concat()?
efi_dp_concat cannot be used to put a device-path end-node in between two device-paths that are concatenated. We need that separator in the load options.
I am not sure I am following you. It's been a few years so please bear with me until I manage to re-read that code and page it back to memory.
What I remember though is that the format of the DP looks like this:
Loaded image DP - end node - initrd GUID DP (without and end node) - initrd - end of device path. So to jump from the special initrd GUID to the actual DP that contains the initrd you need to do an efi_dp_next(). Also, efi_dp_concat() will inject an end node with a DEVICE_PATH_SUB_TYPE_END type if the third argument is 'true'.
What am I missing?
Let us assume
dp1 = /vmlinux/endnode/initrd/endnode dp2 = /dtb/endnode
and we invoke dp_concat(dp1, dp2, true):
sz1 is calculated via the efi_dp_size() function which looks for the *first* device-path end node.
sz1 = efi_dp_size(dp1) = sizeof(/vmlinux)
sz1 will not include initrd and its endnode.
So dp_concat(/vmlinux/endnode/initrd/endnode, /dtb/endnode, true) will return:
/vmlinux/endnode/dtb/endnode
but in our boot option we want
/vmlinux/endnode/initrd/endnode/dtb/endnode
That makes me realize a potential flaw with the design of this boot option. The concept of an initrd is Linux-specific, but the concept of loading a DTB to pass along to an EFI image far less so. So how would this work if I want to only pass the DTB? Would that be:
/vmlinux/endnode/endnode/dtb/endnode
Hello Mark,
We have a VenMedia() device path node with specific GUIDs for initrd and dtb prefixed to these paths. See patch 03/14.
We don't rely on the position. So in your case:
/vmlinux/endnode/dtb/endnode
where the device path 'dtb' would consist of multiple nodes, e.g.:
VenMedia(EFI_FDT_GUID)/HD(1,GPT, ...)/\dir\filename.dtb
Best regards
Heinrich
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