Re: [Xen-devel] [PATCH] Oprofile patch for 2.6.27 tree. Fix collisionbetween Xen and Cell processor escape codes

[Steven Smith <steven.smith@xxxxxxxxxx>]

> > I'm a little confused by this: Upstream oprofile 0.9.4 has 
> > the same workaround implemented on the user mode side of 
> > things, so adjusting this in the kernel now would make the 
> > kernel incompatible with that and future versions. Jan
>   The fact that oprofile user level code has the same workaround
>   is exactly the reason for this patch.
>   We need the same code values in the kernel and in the user level tools.
>   Right now the kernel generates code 13 for DOMAIN_SWITCH_CODE
>   in x86 and Oprofile daemon complains that there is no such code.
>   (it expects code 11 for that).
>   
>   However, your question made me look at Oprofile 0.9.4 and I noticed
>   this workaround changed slightly from 0.9.3 to 0.9.4.
>   The new code checks for powerpc while 0.9.3 checked for
>   x96 and ia64. So we need a slightly different patch.
> 
>   Please use the new attached patch instead of the original one. 
Ian: Can you apply this to the 2.6.27 tree, please?  I'll pull it
through to NC2 from there.

Steven.

>     Fix OProfile escape code collision between Xenoprof's
>     DOMAIN_SWITCH_CODE (in use on x86 and ia64) and Cell's
>     SPU_PROFILING_CODE(in use with Power).
>     
>     Signed-off-by: Jose Renato Santos <jsantos@xxxxxxxxxx>
> 
> diff --git a/include/linux/oprofile.h b/include/linux/oprofile.h
> index bb8a349..8863734 100644
> --- a/include/linux/oprofile.h
> +++ b/include/linux/oprofile.h
> @@ -37,9 +37,18 @@
>  #define TRACE_BEGIN_CODE             8
>  #define TRACE_END_CODE                       9
>  #define XEN_ENTER_SWITCH_CODE                10
> +/*
> + * Ugly work-around for the unfortunate collision between Xenoprof's
> + * DOMAIN_SWITCH_CODE (in use on x86 and ia64) and Cell's SPU_PROFILING_CODE
> + * (in use with Power):
> + */
> +#ifdef CONFIG_PPC
>  #define SPU_PROFILING_CODE           11
>  #define SPU_CTX_SWITCH_CODE          12
>  #define DOMAIN_SWITCH_CODE           13
> +#else
> +#define DOMAIN_SWITCH_CODE           11
> +#endif
>  
>  struct super_block;
>  struct dentry;
> 
> 




> > >>> "Santos, Jose Renato G" <joserenato.santos@xxxxxx> 23.06.09 20:13 
> > >>> >>>
> > 
> > Steven
> > 
> > This is a fix to enable Oprofile to work on the netchannel2 
> > 2.6.27 tree.
> > 
> > This is to address a collision for escape codes used to 
> > represent domain switches in Xen and CPU switches in cell 
> > processors which were developed in parallel and used the same code.
> > 
> > There was a discussion on the Oprofile mailing list a while 
> > ago and it was decided that we would use different Oprofile 
> > codes for x86 and ia64 archs (which are the only ones that 
> > support Oprofile in Xen) in order to preserve backward 
> > compatibility for users.
> > 
> > The Oprofile user level tools expect different escape codes 
> > depending on the architecture. We need to make sure the 
> > kernel generates compatible escape codes.
> > 
> > I think this should be also pushed to the 2.6.27 XenClient tree.
> > 
> > Thanks
> > 
> > Renato
> > 
> >

fix_domain_switch_code.diff
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