[U-Boot] [RFC] bug.h: Drop filename from BUG/WARNING logs if building for TPL/SPL
On several platforms space is very tight when building for SPL or TPL. To claw back a few bytes to be used for code remove the __FILE__ name from the BUG() and WARN() type macros. Since those macros still print the function name plus a line number this should not really affect the ability to backtrace an actual BUG/WARN message to a specific piece of code.
Signed-off-by: Andreas Dannenberg dannenberg@ti.com ---
I was looking for a way to shave off a few bytes from the SPL code size (TI AM335x) and looking at the hexdump of the SPL I found well why not further reduce some strings down in size... I was already aware of the recent compiler optimizations to drop some of the irrelevant path from the __FILE__ macro but I wanted to go one step beyond this. Dropping all the path from __FILE__ via preprocessor macro can't be easily done as others have already found so I decided to drop __FILE__ altogether (code below) and was excited about the improvements I got...
Then of course using Google I found there was prior art, specifically this discussion here:
"[U-Boot] __FILE__ usage and and SPL limits for SRAM" https://patchwork.ozlabs.org/patch/746922/
So I made this submission to "RFC" to simply re-ignite the subject to see if we can somehow find some path to proceed with such a change...
I like about the proposal referenced above that it touches more places than what I came up with, however it is missing the TPL/SPL aspect which I thought would be a good way to alleviate some of the concerns raised (Wolfgang) around not having __FILE__ in the log...
Maybe a combination of the approaches could be workable?
At the end of the day SPL/TPL are intended for very memory-constrained environments, so I feel changes like the proposed that don't really affect any of the existing functionality are good candidates to consider...
Regards, Andreas
include/linux/bug.h | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/linux/bug.h b/include/linux/bug.h index 29f84168a3..36b5fddfae 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -5,9 +5,22 @@ #include <linux/build_bug.h> #include <linux/compiler.h> #include <linux/printk.h> +#include <linux/kconfig.h> + +#if defined(CONFIG_TPL_BUILD) || defined(CONFIG_SPL_BUILD) +/* + * In case of TPL/SPL use a short format not including __FILE__ + * to reduce image size + */ +#define BUG_WARN_LOC_FMT "%d@%s()" +#define BUG_WARN_LOC_ARGS __LINE__, __func__ +#else +#define BUG_WARN_LOC_FMT "%s:%d/%s()" +#define BUG_WARN_LOC_ARGS __FILE__, __LINE__, __func__ +#endif
#define BUG() do { \ - printk("BUG at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \ + printk("BUG at " BUG_WARN_LOC_FMT "!\n", BUG_WARN_LOC_ARGS); \ panic("BUG!"); \ } while (0)
@@ -16,7 +29,7 @@ #define WARN_ON(condition) ({ \ int __ret_warn_on = !!(condition); \ if (unlikely(__ret_warn_on)) \ - printk("WARNING at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \ + printk("WARNING at " BUG_WARN_LOC_FMT "!\n", BUG_WARN_LOC_ARGS); \ unlikely(__ret_warn_on); \ })
On Wed, Jul 10, 2019 at 04:30:44PM -0500, Andreas Dannenberg wrote:
On several platforms space is very tight when building for SPL or TPL. To claw back a few bytes to be used for code remove the __FILE__ name from the BUG() and WARN() type macros. Since those macros still print the function name plus a line number this should not really affect the ability to backtrace an actual BUG/WARN message to a specific piece of code.
Signed-off-by: Andreas Dannenberg dannenberg@ti.com
I was looking for a way to shave off a few bytes from the SPL code size (TI AM335x) and looking at the hexdump of the SPL I found well why not further reduce some strings down in size... I was already aware of the recent compiler optimizations to drop some of the irrelevant path from the __FILE__ macro but I wanted to go one step beyond this. Dropping all the path from __FILE__ via preprocessor macro can't be easily done as others have already found so I decided to drop __FILE__ altogether (code below) and was excited about the improvements I got...
Just some quick examples about the savings...
Using buildman "bloat" reporting (-B) I see the SPL .text size for AM335x to be reduced by 12 bytes. And for AM43xx the size goes down by 52 bytes. The benefit of the proposed change really depends on a) whether a given platform uses SPL, and b) how many calls to BUG/WARN it has. The USB drivers in AM335x/AM43xx are really the "heavy hitters" here. I'm sure I could find additional examples/platforms to highlight savings if needed.
Anyways I'm not proud of the proposed change but merely wanted to see with this RFC if there isn't any way to do further optimizations on the __FILE__ topic that are not overly intrusive specifically as it comes to SPL.
Best Regards, Andreas
Then of course using Google I found there was prior art, specifically this discussion here:
"[U-Boot] __FILE__ usage and and SPL limits for SRAM" https://patchwork.ozlabs.org/patch/746922/
So I made this submission to "RFC" to simply re-ignite the subject to see if we can somehow find some path to proceed with such a change...
I like about the proposal referenced above that it touches more places than what I came up with, however it is missing the TPL/SPL aspect which I thought would be a good way to alleviate some of the concerns raised (Wolfgang) around not having __FILE__ in the log...
Maybe a combination of the approaches could be workable?
At the end of the day SPL/TPL are intended for very memory-constrained environments, so I feel changes like the proposed that don't really affect any of the existing functionality are good candidates to consider...
Regards, Andreas
include/linux/bug.h | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/linux/bug.h b/include/linux/bug.h index 29f84168a3..36b5fddfae 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -5,9 +5,22 @@ #include <linux/build_bug.h> #include <linux/compiler.h> #include <linux/printk.h> +#include <linux/kconfig.h>
+#if defined(CONFIG_TPL_BUILD) || defined(CONFIG_SPL_BUILD) +/*
- In case of TPL/SPL use a short format not including __FILE__
- to reduce image size
- */
+#define BUG_WARN_LOC_FMT "%d@%s()" +#define BUG_WARN_LOC_ARGS __LINE__, __func__ +#else +#define BUG_WARN_LOC_FMT "%s:%d/%s()" +#define BUG_WARN_LOC_ARGS __FILE__, __LINE__, __func__ +#endif
#define BUG() do { \
- printk("BUG at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
- printk("BUG at " BUG_WARN_LOC_FMT "!\n", BUG_WARN_LOC_ARGS); \ panic("BUG!"); \
} while (0)
@@ -16,7 +29,7 @@ #define WARN_ON(condition) ({ \ int __ret_warn_on = !!(condition); \ if (unlikely(__ret_warn_on)) \
printk("WARNING at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
printk("WARNING at " BUG_WARN_LOC_FMT "!\n", BUG_WARN_LOC_ARGS); \})
-- 2.17.1
On Fri, Jul 12, 2019 at 12:34 AM Andreas Dannenberg dannenberg@ti.com wrote:
On Wed, Jul 10, 2019 at 04:30:44PM -0500, Andreas Dannenberg wrote:
On several platforms space is very tight when building for SPL or TPL. To claw back a few bytes to be used for code remove the __FILE__ name from the BUG() and WARN() type macros. Since those macros still print the function name plus a line number this should not really affect the ability to backtrace an actual BUG/WARN message to a specific piece of code.
Signed-off-by: Andreas Dannenberg dannenberg@ti.com
I was looking for a way to shave off a few bytes from the SPL code size (TI AM335x) and looking at the hexdump of the SPL I found well why not further reduce some strings down in size... I was already aware of the recent compiler optimizations to drop some of the irrelevant path from the __FILE__ macro but I wanted to go one step beyond this. Dropping all the path from __FILE__ via preprocessor macro can't be easily done as others have already found so I decided to drop __FILE__ altogether (code below) and was excited about the improvements I got...
Just some quick examples about the savings...
Using buildman "bloat" reporting (-B) I see the SPL .text size for AM335x to be reduced by 12 bytes. And for AM43xx the size goes down by 52 bytes. The benefit of the proposed change really depends on a) whether a given platform uses SPL, and b) how many calls to BUG/WARN it has. The USB drivers in AM335x/AM43xx are really the "heavy hitters" here. I'm sure I could find additional examples/platforms to highlight savings if needed.
Anyways I'm not proud of the proposed change but merely wanted to see with this RFC if there isn't any way to do further optimizations on the __FILE__ topic that are not overly intrusive specifically as it comes to SPL.
Commit 1eb2e71edd55e16562e3912881c449db69623352 was not enough to solve your problem.
Correct?
Yamada-san,
On Fri, Jul 12, 2019 at 02:29:02AM +0900, Masahiro Yamada wrote:
On Fri, Jul 12, 2019 at 12:34 AM Andreas Dannenberg dannenberg@ti.com wrote:
On Wed, Jul 10, 2019 at 04:30:44PM -0500, Andreas Dannenberg wrote:
On several platforms space is very tight when building for SPL or TPL. To claw back a few bytes to be used for code remove the __FILE__ name from the BUG() and WARN() type macros. Since those macros still print the function name plus a line number this should not really affect the ability to backtrace an actual BUG/WARN message to a specific piece of code.
Signed-off-by: Andreas Dannenberg dannenberg@ti.com
I was looking for a way to shave off a few bytes from the SPL code size (TI AM335x) and looking at the hexdump of the SPL I found well why not further reduce some strings down in size... I was already aware of the recent compiler optimizations to drop some of the irrelevant path from the __FILE__ macro but I wanted to go one step beyond this. Dropping all the path from __FILE__ via preprocessor macro can't be easily done as others have already found so I decided to drop __FILE__ altogether (code below) and was excited about the improvements I got...
Just some quick examples about the savings...
Using buildman "bloat" reporting (-B) I see the SPL .text size for AM335x to be reduced by 12 bytes. And for AM43xx the size goes down by 52 bytes. The benefit of the proposed change really depends on a) whether a given platform uses SPL, and b) how many calls to BUG/WARN it has. The USB drivers in AM335x/AM43xx are really the "heavy hitters" here. I'm sure I could find additional examples/platforms to highlight savings if needed.
Anyways I'm not proud of the proposed change but merely wanted to see with this RFC if there isn't any way to do further optimizations on the __FILE__ topic that are not overly intrusive specifically as it comes to SPL.
Commit 1eb2e71edd55e16562e3912881c449db69623352 was not enough to solve your problem.
Correct?
Correct. This is a great commit and I saw what all went into it and it goes a long way in addressing the general concern and doing much needed cleanup but I wanted to go beyond this.
Consider this example, if I use a WARN_ON() deep in the arch folder of one of the SoCs, I would get this on the console...
WARNING at arch/arm/mach-k3/am6_init.c:192/board_init_f()!
...and now, with the proposed change, it would boil down to this...
WARNING at 192@board_init_f()!
If we could just keep the base filename itself that would still be a good size reduction, and keep the output somewhat consistent with the original behavior, but I spent quite some time researching but without some extreme "magic" there didn't seem to be an universal solution...
Also some additional background why I am even looking into this. One of our platforms (AM335x) has a regression building on Travis CI with some of our pending patches applied. Interestingly, this only happens on Travis, which still uses GCC 7.3.0 for arm (why?). With newer, more efficient compilers there is no such issue.
-- Andreas Dannenberg Texas Instruments Inc
On Thu, Jul 11, 2019 at 01:12:16PM -0500, Andreas Dannenberg wrote:
Yamada-san,
On Fri, Jul 12, 2019 at 02:29:02AM +0900, Masahiro Yamada wrote:
On Fri, Jul 12, 2019 at 12:34 AM Andreas Dannenberg dannenberg@ti.com wrote:
On Wed, Jul 10, 2019 at 04:30:44PM -0500, Andreas Dannenberg wrote:
On several platforms space is very tight when building for SPL or TPL. To claw back a few bytes to be used for code remove the __FILE__ name from the BUG() and WARN() type macros. Since those macros still print the function name plus a line number this should not really affect the ability to backtrace an actual BUG/WARN message to a specific piece of code.
Signed-off-by: Andreas Dannenberg dannenberg@ti.com
I was looking for a way to shave off a few bytes from the SPL code size (TI AM335x) and looking at the hexdump of the SPL I found well why not further reduce some strings down in size... I was already aware of the recent compiler optimizations to drop some of the irrelevant path from the __FILE__ macro but I wanted to go one step beyond this. Dropping all the path from __FILE__ via preprocessor macro can't be easily done as others have already found so I decided to drop __FILE__ altogether (code below) and was excited about the improvements I got...
Just some quick examples about the savings...
Using buildman "bloat" reporting (-B) I see the SPL .text size for AM335x to be reduced by 12 bytes. And for AM43xx the size goes down by 52 bytes. The benefit of the proposed change really depends on a) whether a given platform uses SPL, and b) how many calls to BUG/WARN it has. The USB drivers in AM335x/AM43xx are really the "heavy hitters" here. I'm sure I could find additional examples/platforms to highlight savings if needed.
Anyways I'm not proud of the proposed change but merely wanted to see with this RFC if there isn't any way to do further optimizations on the __FILE__ topic that are not overly intrusive specifically as it comes to SPL.
Commit 1eb2e71edd55e16562e3912881c449db69623352 was not enough to solve your problem.
Correct?
Correct. This is a great commit and I saw what all went into it and it goes a long way in addressing the general concern and doing much needed cleanup but I wanted to go beyond this.
Consider this example, if I use a WARN_ON() deep in the arch folder of one of the SoCs, I would get this on the console...
WARNING at arch/arm/mach-k3/am6_init.c:192/board_init_f()!
...and now, with the proposed change, it would boil down to this...
WARNING at 192@board_init_f()!
If we could just keep the base filename itself that would still be a good size reduction, and keep the output somewhat consistent with the original behavior, but I spent quite some time researching but without some extreme "magic" there didn't seem to be an universal solution...
Also some additional background why I am even looking into this. One of our platforms (AM335x) has a regression building on Travis CI with some of our pending patches applied. Interestingly, this only happens on Travis, which still uses GCC 7.3.0 for arm (why?). With newer, more efficient compilers there is no such issue.
On this last point, gcc 7.3 is the current GCC release that doesn't have regressions elsewhere until we reach gcc-9, for which I cannot find good pre-built toolchains. We can get gcc-8.3 (or 8.2? I forget) from Arm Ltd now, but that has problems on x86.
Hi Tom,
On Thu, Jul 11, 2019 at 02:43:17PM -0400, Tom Rini wrote:
On Thu, Jul 11, 2019 at 01:12:16PM -0500, Andreas Dannenberg wrote:
<snip>
Also some additional background why I am even looking into this. One of our platforms (AM335x) has a regression building on Travis CI with some of our pending patches applied. Interestingly, this only happens on Travis, which still uses GCC 7.3.0 for arm (why?). With newer, more efficient compilers there is no such issue.
On this last point, gcc 7.3 is the current GCC release that doesn't have regressions elsewhere until we reach gcc-9, for which I cannot find good pre-built toolchains. We can get gcc-8.3 (or 8.2? I forget) from Arm Ltd now, but that has problems on x86.
Thanks for the background Tom, I wondered about the reasons behind.
Regards, Andreas
-- Andreas Dannenberg Texas Instruments Inc
Hi Andreas,
On Fri, Jul 12, 2019 at 3:12 AM Andreas Dannenberg dannenberg@ti.com wrote:
Yamada-san,
On Fri, Jul 12, 2019 at 02:29:02AM +0900, Masahiro Yamada wrote:
On Fri, Jul 12, 2019 at 12:34 AM Andreas Dannenberg dannenberg@ti.com wrote:
On Wed, Jul 10, 2019 at 04:30:44PM -0500, Andreas Dannenberg wrote:
On several platforms space is very tight when building for SPL or TPL. To claw back a few bytes to be used for code remove the __FILE__ name from the BUG() and WARN() type macros. Since those macros still print the function name plus a line number this should not really affect the ability to backtrace an actual BUG/WARN message to a specific piece of code.
Signed-off-by: Andreas Dannenberg dannenberg@ti.com
I was looking for a way to shave off a few bytes from the SPL code size (TI AM335x) and looking at the hexdump of the SPL I found well why not further reduce some strings down in size... I was already aware of the recent compiler optimizations to drop some of the irrelevant path from the __FILE__ macro but I wanted to go one step beyond this. Dropping all the path from __FILE__ via preprocessor macro can't be easily done as others have already found so I decided to drop __FILE__ altogether (code below) and was excited about the improvements I got...
Just some quick examples about the savings...
Using buildman "bloat" reporting (-B) I see the SPL .text size for AM335x to be reduced by 12 bytes. And for AM43xx the size goes down by 52 bytes. The benefit of the proposed change really depends on a) whether a given platform uses SPL, and b) how many calls to BUG/WARN it has. The USB drivers in AM335x/AM43xx are really the "heavy hitters" here. I'm sure I could find additional examples/platforms to highlight savings if needed.
Anyways I'm not proud of the proposed change but merely wanted to see with this RFC if there isn't any way to do further optimizations on the __FILE__ topic that are not overly intrusive specifically as it comes to SPL.
Commit 1eb2e71edd55e16562e3912881c449db69623352 was not enough to solve your problem.
Correct?
Correct. This is a great commit and I saw what all went into it and it goes a long way in addressing the general concern and doing much needed cleanup but I wanted to go beyond this.
Consider this example, if I use a WARN_ON() deep in the arch folder of one of the SoCs, I would get this on the console...
WARNING at arch/arm/mach-k3/am6_init.c:192/board_init_f()!...and now, with the proposed change, it would boil down to this...
WARNING at 192@board_init_f()!If we could just keep the base filename itself that would still be a good size reduction, and keep the output somewhat consistent with the original behavior, but I spent quite some time researching but without some extreme "magic" there didn't seem to be an universal solution...
Also some additional background why I am even looking into this. One of our platforms (AM335x) has a regression building on Travis CI with some of our pending patches applied. Interestingly, this only happens on Travis, which still uses GCC 7.3.0 for arm (why?). With newer, more efficient compilers there is no such issue.
OK, then. Thanks for explanation.
On Wed, Jul 10, 2019 at 04:30:44PM -0500, Andreas Dannenberg wrote:
On several platforms space is very tight when building for SPL or TPL. To claw back a few bytes to be used for code remove the __FILE__ name from the BUG() and WARN() type macros. Since those macros still print the function name plus a line number this should not really affect the ability to backtrace an actual BUG/WARN message to a specific piece of code.
Signed-off-by: Andreas Dannenberg dannenberg@ti.com
I was looking for a way to shave off a few bytes from the SPL code size (TI AM335x) and looking at the hexdump of the SPL I found well why not further reduce some strings down in size... I was already aware of the recent compiler optimizations to drop some of the irrelevant path from the __FILE__ macro but I wanted to go one step beyond this. Dropping all the path from __FILE__ via preprocessor macro can't be easily done as others have already found so I decided to drop __FILE__ altogether (code below) and was excited about the improvements I got...
Then of course using Google I found there was prior art, specifically this discussion here:
"[U-Boot] __FILE__ usage and and SPL limits for SRAM" https://patchwork.ozlabs.org/patch/746922/
So I made this submission to "RFC" to simply re-ignite the subject to see if we can somehow find some path to proceed with such a change...
I like about the proposal referenced above that it touches more places than what I came up with, however it is missing the TPL/SPL aspect which I thought would be a good way to alleviate some of the concerns raised (Wolfgang) around not having __FILE__ in the log...
Maybe a combination of the approaches could be workable?
At the end of the day SPL/TPL are intended for very memory-constrained environments, so I feel changes like the proposed that don't really affect any of the existing functionality are good candidates to consider...
Regards, Andreas
include/linux/bug.h | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-)
diff --git a/include/linux/bug.h b/include/linux/bug.h index 29f84168a3..36b5fddfae 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -5,9 +5,22 @@ #include <linux/build_bug.h> #include <linux/compiler.h> #include <linux/printk.h> +#include <linux/kconfig.h>
+#if defined(CONFIG_TPL_BUILD) || defined(CONFIG_SPL_BUILD) +/*
- In case of TPL/SPL use a short format not including __FILE__
- to reduce image size
- */
+#define BUG_WARN_LOC_FMT "%d@%s()" +#define BUG_WARN_LOC_ARGS __LINE__, __func__ +#else +#define BUG_WARN_LOC_FMT "%s:%d/%s()" +#define BUG_WARN_LOC_ARGS __FILE__, __LINE__, __func__ +#endif
#define BUG() do { \
- printk("BUG at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
- printk("BUG at " BUG_WARN_LOC_FMT "!\n", BUG_WARN_LOC_ARGS); \ panic("BUG!"); \
} while (0)
@@ -16,7 +29,7 @@ #define WARN_ON(condition) ({ \ int __ret_warn_on = !!(condition); \ if (unlikely(__ret_warn_on)) \
printk("WARNING at %s:%d/%s()!\n", __FILE__, __LINE__, __func__); \
printk("WARNING at " BUG_WARN_LOC_FMT "!\n", BUG_WARN_LOC_ARGS); \})
I know this is RFC but I think I'm really fine with it. With respect to SPL failures we have: - Developer is developing. It's not unreasonable to expect the developer to be able to figure out what the file is that the message came from. - Deployed, no one should see this ever, so it doesn't matter. - Deployed, vendor asks customer to pull up debug interface (or vendor tech is onsite, pulls up debug interface, etc). Still a reasonable expectation that the person seeing the log will be able to work things out with function/line numbers.
I'm not applying this right away, but I expect to soon.
participants (3)
-
Andreas Dannenberg -
Masahiro Yamada -
Tom Rini