Re: [XenPPC] [PATCH] Linker script causes SMP memory corruption

[Jimi Xenidis <jimix@xxxxxxxxxxxxxx>]

Ahh, this stuff is so wonky it is so easy to miss the _real_ reason :)

On Aug 19, 2006, at 2:22 AM, Amos Waterland wrote:
> To understand the context for this patch, observe that the  
> following is
> the case in stock Xen/PPC:
>
>  $ nm xen-syms | egrep ' per_cpu__|__per_cpu' | sort
>  000000000044c680 d per_cpu__domain_shuttingdown
>  000000000044c688 D per_cpu__mc_state
>  000000000044c700 d per_cpu__t_timer
>  ...
>  000000000045cc80 D per_cpu__tlbflush_time
>  000000000045d2b0 A __per_cpu_data_end
>  000000000045d2b0 A __per_cpu_start
>  0000000000460000 A __per_cpu_end
So what is actually happening is that your .data.percpu sections are  
getting sucked up by the linker before the section description we  
actually want to be used.
This is the correct fix (possible MUA mangling):

diff -r 539a1e666982 xen/arch/powerpc/xen.lds.S
--- a/xen/arch/powerpc/xen.lds.S        Fri Aug 18 14:07:50 2006 -0400
+++ b/xen/arch/powerpc/xen.lds.S        Sun Aug 20 10:57:46 2006 -0400
@@ -107,7 +107,7 @@ SECTIONS
   PROVIDE (__fini_array_end = .);
   .data           :
   {
-    *(.data .data.* .gnu.linkonce.d.*)
+    *(.data .gnu.linkonce.d.*)
     SORT(CONSTRUCTORS)
   }

this .data.* catch-all got your sections before the one we define  
even had a chance :)
I'll commit this fix when I fix everything else I broke :-D

-JX


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