Hi Albert,
On Friday, April 5, 2013 1:54:38 AM, Albert ARIBAUD wrote:
Hi Benoît,
On Fri, 5 Apr 2013 01:13:51 +0200 (CEST), Benoît Thébaudeau benoit.thebaudeau@advansee.com wrote:
On Friday, April 5, 2013 1:05:53 AM, Benoît Thébaudeau wrote:
Hi Albert,
On Friday, April 5, 2013 12:13:53 AM, Albert ARIBAUD wrote:
Subject: [PATCH] ARM: Fix __bss_start and __bss_end in linker scripts
Commit 3ebd1cbc introduced compiler-generated __bss_start and __bss_end__ and commit c23561e7 rewrote all __bss_end__ as __bss_end. Their merge caused silent and harmless but potentially bug-inducing clashes between compiler- and linker- enerated __bss_end symbols.
Make __bss_end and __bss_start compiler-only, and create __bss_base and __bss_limit for linker-only use.
Reported-by: Benoît Thébaudeau benoit.thebaudeau@advansee.com Signed-off-by: Albert ARIBAUD albert.u.boot@aribaud.net
arch/arm/cpu/ixp/u-boot.lds | 14 ++++++++++---- arch/arm/cpu/u-boot.lds | 14 ++++++++++---- board/actux1/u-boot.lds | 14 ++++++++++---- board/actux2/u-boot.lds | 14 ++++++++++---- board/actux3/u-boot.lds | 14 ++++++++++---- board/dvlhost/u-boot.lds | 14 ++++++++++---- board/freescale/mx31ads/u-boot.lds | 14 ++++++++++---- 7 files changed, 70 insertions(+), 28 deletions(-)
diff --git a/arch/arm/cpu/ixp/u-boot.lds b/arch/arm/cpu/ixp/u-boot.lds index 8345b55..c999829 100644 --- a/arch/arm/cpu/ixp/u-boot.lds +++ b/arch/arm/cpu/ixp/u-boot.lds @@ -67,17 +67,23 @@ SECTIONS
_end = .;
+/*
- Compiler-generated __bss_start and __bss_end, see
arch/arm/lib/bss.c
- __bss_base and __bss_limit are for linker only (overlay ordering)
- */
- .bss_start __rel_dyn_start (OVERLAY) : { KEEP(*(.__bss_start));
HIDDEN(__bss_base = .);
- .bss __bss_start (OVERLAY) : {
- .bss __bss_base (OVERLAY) : { *(.bss*) . = ALIGN(4);
__bss_end = .;
HIDDEN(__bss_limit = .);
- .bss_end __bss_end (OVERLAY) : {
KEEP(*(__bss_end));
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.__bss_end));}
/DISCARD/ : { *(.dynstr*) }
diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds index 3a1083d..0543b06 100644 --- a/arch/arm/cpu/u-boot.lds +++ b/arch/arm/cpu/u-boot.lds @@ -81,18 +81,24 @@ SECTIONS *(.mmutable) }
+/*
- Compiler-generated __bss_start and __bss_end, see
arch/arm/lib/bss.c
- __bss_base and __bss_limit are for linker only (overlay ordering)
- */
- .bss_start __rel_dyn_start (OVERLAY) : { KEEP(*(.__bss_start));
HIDDEN(__bss_base = .);
- .bss __bss_start (OVERLAY) : {
- .bss __bss_base (OVERLAY) : { *(.bss*) . = ALIGN(4);
__bss_end = .;
HIDDEN(__bss_limit = .);
- .bss_end __bss_end (OVERLAY) : {
KEEP(*(__bss_end));
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.__bss_end));}
/DISCARD/ : { *(.dynstr*) }
diff --git a/board/actux1/u-boot.lds b/board/actux1/u-boot.lds index c76728a..7e5c4d8 100644 --- a/board/actux1/u-boot.lds +++ b/board/actux1/u-boot.lds @@ -74,17 +74,23 @@ SECTIONS
_end = .;
+/*
- Compiler-generated __bss_start and __bss_end, see
arch/arm/lib/bss.c
- __bss_base and __bss_limit are for linker only (overlay ordering)
- */
- .bss_start __rel_dyn_start (OVERLAY) : { KEEP(*(.__bss_start));
HIDDEN(__bss_base = .);
- .bss __bss_start (OVERLAY) : {
- .bss __bss_base (OVERLAY) : { *(.bss*) . = ALIGN(4);
__bss_end = .;
HIDDEN(__bss_limit = .);
- .bss_end __bss_end (OVERLAY) : {
KEEP(*(__bss_end));
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.__bss_end));}
/DISCARD/ : { *(.dynstr*) }
diff --git a/board/actux2/u-boot.lds b/board/actux2/u-boot.lds index 984f70e..ce1b7c9 100644 --- a/board/actux2/u-boot.lds +++ b/board/actux2/u-boot.lds @@ -74,17 +74,23 @@ SECTIONS
_end = .;
+/*
- Compiler-generated __bss_start and __bss_end, see
arch/arm/lib/bss.c
- __bss_base and __bss_limit are for linker only (overlay ordering)
- */
- .bss_start __rel_dyn_start (OVERLAY) : { KEEP(*(.__bss_start));
HIDDEN(__bss_base = .);
- .bss __bss_start (OVERLAY) : {
- .bss __bss_base (OVERLAY) : { *(.bss*) . = ALIGN(4);
__bss_end = .;
HIDDEN(__bss_limit = .);
- .bss_end __bss_end (OVERLAY) : {
KEEP(*(__bss_end));
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.__bss_end));}
/DISCARD/ : { *(.dynstr*) }
diff --git a/board/actux3/u-boot.lds b/board/actux3/u-boot.lds index fc48cf0..3e091dd 100644 --- a/board/actux3/u-boot.lds +++ b/board/actux3/u-boot.lds @@ -74,17 +74,23 @@ SECTIONS
_end = .;
+/*
- Compiler-generated __bss_start and __bss_end, see
arch/arm/lib/bss.c
- __bss_base and __bss_limit are for linker only (overlay ordering)
- */
- .bss_start __rel_dyn_start (OVERLAY) : { KEEP(*(.__bss_start));
HIDDEN(__bss_base = .);
- .bss __bss_start (OVERLAY) : {
- .bss __bss_base (OVERLAY) : { *(.bss*) . = ALIGN(4);
__bss_end = .;
HIDDEN(__bss_limit = .);
- .bss_end __bss_end (OVERLAY) : {
KEEP(*(__bss_end));
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.__bss_end));}
/DISCARD/ : { *(.dynstr*) }
diff --git a/board/dvlhost/u-boot.lds b/board/dvlhost/u-boot.lds index b13d3e1..fe3c21b 100644 --- a/board/dvlhost/u-boot.lds +++ b/board/dvlhost/u-boot.lds @@ -74,17 +74,23 @@ SECTIONS
_end = .;
+/*
- Compiler-generated __bss_start and __bss_end, see
arch/arm/lib/bss.c
- __bss_base and __bss_limit are for linker only (overlay ordering)
- */
- .bss_start __rel_dyn_start (OVERLAY) : { KEEP(*(.__bss_start));
HIDDEN(__bss_base = .);
- .bss __bss_start (OVERLAY) : {
- .bss __bss_base (OVERLAY) : { *(.bss*) . = ALIGN(4);
__bss_end = .;
HIDDEN(__bss_limit = .);
- .bss_end __bss_end (OVERLAY) : {
KEEP(*(__bss_end));
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.__bss_end));}
/DISCARD/ : { *(.dynstr*) }
diff --git a/board/freescale/mx31ads/u-boot.lds b/board/freescale/mx31ads/u-boot.lds index 264c4e8..e6885a5 100644 --- a/board/freescale/mx31ads/u-boot.lds +++ b/board/freescale/mx31ads/u-boot.lds @@ -80,17 +80,23 @@ SECTIONS
_end = .;
+/*
- Compiler-generated __bss_start and __bss_end, see
arch/arm/lib/bss.c
- __bss_base and __bss_limit are for linker only (overlay ordering)
- */
- .bss_start __rel_dyn_start (OVERLAY) : { KEEP(*(.__bss_start));
HIDDEN(__bss_base = .);
- .bss __bss_start (OVERLAY) : {
- .bss __bss_base (OVERLAY) : { *(.bss*) . = ALIGN(4);
__bss_end = .;
HIDDEN(__bss_limit = .);
- .bss_end __bss_end (OVERLAY) : {
KEEP(*(__bss_end));
.bss_end __bss_limit (OVERLAY) : {
KEEP(*(.__bss_end));}
/DISCARD/ : { *(.bss*) }
-- 1.7.10.4
Looks good, but what about the __bss_end in ASSERT(__bss_end < (CONFIG_SPL_TEXT_BASE + CONFIG_SPL_MAX_SIZE), "SPL image too big"); ?
Shouldn't it be replaced with __bss_limit, or even better, with __image_copy_end (why should BSS be taken into account for SPL image size?)?
I meant __bss_base, not __image_copy_end.
Part of SPL can use BSS, once board_init_f() has handed things over to board_init_r(),
I agree with that.
and this test is meant to ensure that .text+.data+.bss fits in the RAM available to SPL. This ASSERT() compares the upper limit of this RAM to the upper limit of the SPL needs, i.e. __bss_end.
IOW, this ASSERT is about how much memory SPL will use when it runs,
This is where there might be an issue with the definition / usage of CONFIG_SPL_MAX_SIZE.
I had understood that this is the purpose of this assert, but this usage of CONFIG_SPL_MAX_SIZE, while frequent on arm, conflicts with its definition in README, as well as with some arm and other usages, e.g. in include/configs/am335x_evm.h or include/configs/p1_p2_rdb_pc.h.
The README's definition is also how I understood this config when discussing it with Scott about my 16/30, which led to the #error test that was added at some point to this patch.
According to README, CONFIG_SPL_MAX_SIZE is for text + data + rodata (i.e. for the size of the binary image file to be programmed on the target device), while CONFIG_SPL_BSS_MAX_SIZE is dedicated to the BSS. Hence, in order to comply with this definition, that assert should either use __bss_base/__bss_start, or compare against CONFIG_SPL_MAX_SIZE + CONFIG_SPL_BSS_MAX_SIZE, depending on whether it's supposed to test the binary image size or the memory footprint. There could even be asserts testing both. This would anyway be a new patch separate from this one.
If you decided not to change that, CONFIG_SPL_MAX_SIZE would have different meanings depending on the board, and CONFIG_SPL_PAD_TO could be smaller than it in some cases, so the #error test in my 16/30 could be removed, but no such case exists so far, making this 16/30 change not strictly necessary for now.
while OTOH, image_copy_end is about how much code from SPL need to becopied from e.g. NAND to RAM to make it run.
Right.
As for bss_limit, as indicated, it is only for linker convenience, so that overlaid sections are mapped properly; it should not be used to signify something about the image itself)
OK, I'm fine with that. They have the same value, so it's only a matter of taste. I spotted that just because you said __bss_limit is for linker stuff, and it is an assert for the linker, but __bss_end is just fine too, all the more the resulting assert is then identical to the one in arch/arm/cpu/u-boot-spl.lds.
Best regards, Benoît