[U-Boot] [RFC PATCH] arm: lds: Remove libgcc eabi exception handling tables

[Michal Simek]

On 05/10/2013 09:07 PM, Albert ARIBAUD wrote:
> Hi Michal,
> 
> On Thu,  9 May 2013 11:35:33 +0200, Michal Simek
> <michal.simek at xilinx.com> wrote:
> 
>> Remove ARM eabi exception handling tables (for frame unwinding).
>> AFAICT, u-boot stubs away the frame unwiding routines, so the tables will
>> more or less just consume space. It should be OK to remove them.
>>
>> Signed-off-by: Edgar E. Iglesias <edgar.iglesias at xilinx.com>
>> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
>> ---
>> Other options could be to complete u-boot/arch/arm/lib/* so that
>> libgcc routines with exception handling dont get pulled in. Or
>> to avoid user code (like the mentioned patch) which causes external
>> libgcc functions to get pulled in...
> 
> Er... which mentioned patch?

Ah yeah. Let me give you background.
After adding:
"arm: zynq: U-Boot udelay < 1000 FIX"
(sha1: d54cc007878697a92e7f696b71a3eb203c0386e2)

we have found that new program header is added to u-boot for zynq.

Program Header:
0x70000001 off    0x000405fc vaddr 0x040385fc paddr 0x040385fc align 2**2
         filesz 0x00000020 memsz 0x00000020 flags r--
    LOAD off    0x00008000 vaddr 0x04000000 paddr 0x04000000 align 2**15
         filesz 0x00041240 memsz 0x00041240 flags rwx
   STACK off    0x00000000 vaddr 0x00000000 paddr 0x00000000 align 2**2
         filesz 0x00000000 memsz 0x00000000 flags rwx

Tracing down this we found that uldivmod is used
    27: 00000000     0 NOTYPE  GLOBAL DEFAULT  UND __aeabi_uldivmod

Based on that Edgar proposed this patch.

After my experiment we can also use the patch below to fix it
because external libgcc functions are not pulled it.
But probably removing that ARM eabi exception handling tables is better
solution then try to change code not to use it.
But for me it is no problem to send the patch below to fix this problem.

Thanks,
Michal

diff --git a/arch/arm/cpu/armv7/zynq/timer.c b/arch/arm/cpu/armv7/zynq/timer.c
index 1b56373..4b26e96 100644
--- a/arch/arm/cpu/armv7/zynq/timer.c
+++ b/arch/arm/cpu/armv7/zynq/timer.c
@@ -118,12 +118,13 @@ void __udelay(unsigned long usec)
        u32 timeend;
        u32 timediff;
        u32 timenow;
+       u64 temp;

        if (usec == 0)
                return;

-       countticks = (u32) (((unsigned long long) TIMER_TICK_HZ * usec) /
-                                                               1000000);
+       temp = (TIMER_TICK_HZ * usec) / 1000000;
+       countticks = (u32)temp;

        /* decrementing timer */
        timeend = readl(&timer_base->counter) - countticks;



-- 
Michal Simek, Ing. (M.Eng), OpenPGP -> KeyID: FE3D1F91
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel - Microblaze cpu - http://www.monstr.eu/fdt/
Maintainer of Linux kernel - Xilinx Zynq ARM architecture
Microblaze U-BOOT custodian and responsible for u-boot arm zynq platform


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