PATCH: Fix VMI and COMPAT_VDSO for 2.6.21

PATCH: Fix VMI and COMPAT_VDSO for 2.6.21

[Zachary Amsden]

VMI is broken under COMPAT_VDSO, as Xen and other non hardware assisted 
hypervisors will be.  I have been working on a fix for this which works 
for older glibcs that panic when the new relocatable VDSO is used.  
However, I believe at this time that the fix is going to be too radical 
to consider at this stage in the release of 2.6.21.  We don't expect 
this config option to be turned on by vendors for new distributions, so 
at this point we are willing to drop support for it when VMI is compiled 
in, and work on a patch for 2.6.22 which more fully addresses the problem.

Please apply, thanks.

Zach

Re: PATCH: Fix VMI and COMPAT_VDSO for 2.6.21

[Zachary Amsden]

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Zachary Amsden wrote:
> VMI is broken under COMPAT_VDSO, as Xen and other non hardware 
> assisted hypervisors will be.  I have been working on a fix for this 
> which works for older glibcs that panic when the new relocatable VDSO 
> is used.  However, I believe at this time that the fix is going to be 
> too radical to consider at this stage in the release of 2.6.21.  We 
> don't expect this config option to be turned on by vendors for new 
> distributions, so at this point we are willing to drop support for it 
> when VMI is compiled in, and work on a patch for 2.6.22 which more 
> fully addresses the problem.
>
> Please apply, thanks.

I suppose it would be better if I attached the patch.

Zach

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Signed-off-by: Zachary Amsden <zach@vmware.com>

Index: linux-2.6.21/arch/i386/Kconfig
===================================================================
--- linux-2.6.21.orig/arch/i386/Kconfig	2007-03-06 18:51:33.000000000 -0800
+++ linux-2.6.21/arch/i386/Kconfig	2007-03-09 22:36:15.000000000 -0800
@@ -220,7 +220,7 @@ config PARAVIRT
 
 config VMI
 	bool "VMI Paravirt-ops support"
-	depends on PARAVIRT
+	depends on PARAVIRT && !COMPAT_VDSO
 	help
 	  VMI provides a paravirtualized interface to the VMware ESX server
 	  (it could be used by other hypervisors in theory too, but is not

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Re: PATCH: Fix VMI and COMPAT_VDSO for 2.6.21

[Ingo Molnar]

* Zachary Amsden <zach@vmware.com> wrote:

> Zachary Amsden wrote:
> >VMI is broken under COMPAT_VDSO, as Xen and other non hardware 
> >assisted hypervisors will be.  I have been working on a fix for this 
> >which works for older glibcs that panic when the new relocatable VDSO 
> >is used.  However, I believe at this time that the fix is going to be 
> >too radical to consider at this stage in the release of 2.6.21.  We 
> >don't expect this config option to be turned on by vendors for new 
> >distributions, so at this point we are willing to drop support for it 
> >when VMI is compiled in, and work on a patch for 2.6.22 which more 
> >fully addresses the problem.
> >
> >Please apply, thanks.

makes sense. We can do Jan's relocatable-COMPAT_VDSO thing in v2.6.22, 
but for v2.6.21 that's way too intrusive.

Acked-by: Ingo Molnar <mingo@elte.hu>

> I suppose it would be better if I attached the patch.

it certainly helps ;-)

	Ingo

Re: PATCH: Fix VMI and COMPAT_VDSO for 2.6.21

[Zachary Amsden]

Ingo Molnar wrote:
> makes sense. We can do Jan's relocatable-COMPAT_VDSO thing in v2.6.22, 
> but for v2.6.21 that's way too intrusive.
>   

Agree.  I think we can clean up some of the strange build magic though, 
by adding boot time ELF magic instead.  We'll see which works out better.

Zach