Hi Andreas,
On 07/05/2012 11:38 PM, Andreas Bießmann wrote:
Dear Zhong Hongbo,
this is arm related and should therefore apply to all the different arch/arm/cpu/*/start.S (as long as they have SPL support).
Ok, I will do it. Thanks for your advise.
On 05.07.2012 16:35, Zhong Hongbo wrote:
From: Zhong Hongbo bocui107@gmail.com
In currently, when __bss_start is equal to __bss_end__, The bss loop will clear all the things in memory space.
I ask myself why there is no bss at all. Have you just initialized data in your spl code?
Yes
But just only when __bss_end__ greater than __bss_start__, we do the clear bss section operation.
Signed-off-by: Hongbo Zhong bocui107@gmail.com
arch/arm/cpu/armv7/start.S | 9 ++++++--- 1 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S index 22a3ced..2e583ee 100644 --- a/arch/arm/cpu/armv7/start.S +++ b/arch/arm/cpu/armv7/start.S @@ -259,10 +259,13 @@ clear_bss: #endif mov r2, #0x00000000 /* clear */
-clbss_l:str r2, [r0] /* clear loop... */ +clbss_l:
- cmp r1, r0
- bls clbss_end
- str r2, [r0] /* clear loop... */ add r0, r0, #4
- cmp r0, r1
- bne clbss_l
- b clbss_l
+clbss_end:
Looks sane, I maybe had checked before clbss_l, jumped over clear loop if r0 and r1 equal (to emphasize the fact that this is a check for entry correctness) and wouldn't change the loop at all. To be more precise we could also check if end is after start.
I check the starts of arm92ejs, I found the issue display in other arm platform. As following:
commit 8f1da53508c78789ebeea98a92a3f55c3f84dc5d Author: Christian Riesch christian.riesch@omicron.at Date: Wed Nov 30 22:27:37 2011 +0000
arm, arm926ejs: Fix clear bss loop for zero length bss
This patch fixes the clear bss loop for bss sections that have zero length, i.e., where __bss_start == __bss_end__.
Signed-off-by: Christian Riesch christian.riesch@omicron.at Cc: Albert Aribaud albert.u.boot@aribaud.net
diff --git a/arch/arm/cpu/arm926ejs/start.S b/arch/arm/cpu/arm926ejs/start.S index 339c5ed..bb4d00b 100644 --- a/arch/arm/cpu/arm926ejs/start.S +++ b/arch/arm/cpu/arm926ejs/start.S @@ -301,10 +301,12 @@ clear_bss: #endif mov r2, #0x00000000 /* clear */
-clbss_l:str r2, [r0] /* clear loop... */ +clbss_l:cmp r0, r1 /* clear loop... */ + bhs clbss_e /* if reached end of bss, exit */ + str r2, [r0] add r0, r0, #4 - cmp r0, r1 - bne clbss_l + b clbss_l +clbss_e:
Thanks, hongbo
/*
- We are done. Do not return, instead branch to second part of board
Best regards
Andreas Bießmann