On 10/18/2012 02:58 PM, Stephen Warren wrote:
On 10/18/2012 02:36 PM, Albert ARIBAUD wrote:
Hi Stephen,
On Wed, 17 Oct 2012 21:17:45 -0600, Stephen Warren swarren@wwwdotorg.org wrote:
On 10/17/2012 05:58 PM, Simon Glass wrote:
Hi Stephen,
On Tue, Oct 16, 2012 at 2:50 PM, Stephen Warren swarren@wwwdotorg.org wrote:
From: Stephen Warren swarren@nvidia.com
When -ffunction-sections or -fdata-section are used, symbols are placed into sections such as .data.eserial1_device and .bss.serial_current. Update the linker script to explicitly include these. Without this change (at least with my gcc-4.5.3 built using crosstool-ng), I see that the sections do end up being included, but __bss_end__ gets set to the same value as __bss_start.
Signed-off-by: Stephen Warren swarren@nvidia.com
This series fixes an SPL size overflow problem on Tegra. Tom Warren is out on vacation until Oct 25th, so he certainly won't be able to review this. Perhaps it could be applied directly to the ARM tree if enough Tegra people ack the series?
Note that this series is not enough to make Tegra support work; either you must hack ./arch/arm/cpu/arm720t/tegra-common/spl.c to call serial_initialize() right before serial_init() in preloader_console_init() or wait for Allen Martin to rework Tegra's SPL support using the common SPL code.
Are you going to submit a patch to enable function-sections, or is that a separate discussion?
For the SPL on Tegra, those flags were already on; this patch fixes a bug rather than prepares for new functionality.
diff --git a/arch/arm/cpu/u-boot.lds b/arch/arm/cpu/u-boot.lds
.u_boot_cmd : { *(.u_boot_cmd) }
.u_boot_cmd : { *(.u_boot_cmd*) }I don't think this line is needed?
...
*(.dynsym)
*(.dynsym*)Nor this one?
Possibly. I changed all the section names to be future-proof. Perhaps a more targeted patch is warranted.
Has this been (at least build-)tested on all boards which have -ffunction-sections or -fdata-sections?
Yes; those flags both appear to be turned on when building the SPL for Tegra (although strangely, not when building the main U-Boot):
xxx-gcc -M -g -Os -fno-common -ffixed-r8 -msoft-float -D__KERNEL__ -ffunction-sections -fdata-sections -DCONFIG_SYS_TEXT_BASE=0x0010c000 -DCONFIG_SPL_TEXT_BASE=0x00108000 -DCONFIG_SPL_BUILD -I/home/swarren/shared/git_wa/u-boot/include -fno-builtin -ffreestanding -nostdinc -isystem xxx -pipe -DCONFIG_ARM -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -march=armv4 -mtune=arm7tdmi -MQ xxx/spl/arch/arm/cpu/arm720t/interrupts.o interrupts.c > xxx/spl/arch/arm/cpu/arm720t/.depend.interrupts
I tried to test this more widely. I found that only arch/arm/cpu/ixp/config.mk enables this on ARM, with the comment:
# -fdata-sections triggers "section .bss overlaps section .rel.dyn" linker error PLATFORM_RELFLAGS += -ffunction-sections LDFLAGS_u-boot += --gc-sections
Indeed, if I edit arch/arm/cpu/armv7/config.mk to enable both -ffunction-sections -fdata-sections, I do see that same section overlap error building for Tegra.
Then, if I apply the .lds patch we're discussing, Tegra builds (and runs) OK with those linker flags enabled. So, this patch seems to fix two issues not just one - bonus:-)