Re: [Fastboot] [CFT] ELF Relocatable x86 and x86_64 bzImages

[Don Zickus]

> Looking at my build it appears bytes_out is being placed in the .bss.
> A little odd since it is zero initialized but no big deal.
> Could you confirm that bytes_out is being placed in the .bss section 
> by inspecting arch/x86_64/boot/compresssed/misc.o and
> arch/x86_64/boot_compressed/vmlinux.   "readelf -a $file" and then
> looking up the section number and looking at the section table to see
> which section it is was my technique.
> 
> If bytes_out is in the .bss for you then I suspect something is not
> correctly zeroing the .bss.  Or else the .bss is being stomped.
> 
> I'm not certain how rep stosb can be done wrong but some bad pointer
> math could have done it.
> 
> Eric

It seems Vivek came up with a solution that works.  He sent it to me this
morning.  We tested a bunch of machines and things seem to work now.  It
looks like it mimics the i386 behaviour now.

Cheers,
Don

Signed-off-by: Vivek Goyal <vgoyal@xxxxxxxxxx>
---

 arch/x86_64/boot/compressed/head.S |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff -puN arch/x86_64/boot/compressed/head.S~x86_64-bss-clearing-test
arch/x86_64/boot/compressed/head.S
---
linux-2.6.18-rc3-1M/arch/x86_64/boot/compressed/head.S~x86_64-bss-clearing-test
2006-08-09 09:43:17.000000000 -0400
+++ linux-2.6.18-rc3-1M-root/arch/x86_64/boot/compressed/head.S 2006-08-09
09:43:34.000000000 -0400
@@ -235,8 +235,8 @@ relocated:
 /*
  * Clear BSS
  */
-       movq    $_edata, %rdi
-       movq    $_end, %rcx
+        leaq    _edata(%rbx), %rdi
+        leaq    _end(%rbx), %rcx
        subq    %rdi, %rcx
        cld
        rep
_

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