Re: [PATCH] KVM: VMX: Correct asm constraint in vmcs_load()

[Randy Dunlap <randy.dunlap@oracle.com>]

On 12/20/10 09:58, Avi Kivity wrote:
> On 12/20/2010 07:57 PM, Avi Kivity wrote:
>> On 12/20/2010 07:53 PM, Randy Dunlap wrote:
>>> On 12/20/10 09:47, Avi Kivity wrote:
>>> >  On 12/20/2010 06:56 PM, Randy Dunlap wrote:
>>> >>  On 12/20/10 01:06, Avi Kivity wrote:
>>> >> >   'error' is byte sized, so use a byte register constraint.
>>> >>
>>> >>  Hm, OK, but I still get the same build error.
>>> >
>>> >  Not okay then.  Can you verify that by removing the content of the
>>> >  function the problem goes away?
>>>
>>> Nope.  I put #if 0 / #endif around the asm() and if (error) lines
>>> but I still get the error message:
>>>
>>> linux-next-20101217/arch/x86/kvm/vmx.c: Assembler messages:
>>> linux-next-20101217/arch/x86/kvm/vmx.c:488: Error: bad register name
>>> `%sil'
>>>
>>
>> And line 488 was one of those under #if 0?
>>
>>> which is on the "u8 error;" line below:
>>>
>>> static void vmcs_load(struct vmcs *vmcs)
>>> {
>>>     u64 phys_addr = __pa(vmcs);
>>>     u8 error;
>>>
> 
> Er, you just answered me.  Are you sure gcc saw your update?  what
> happens if you comment that line as well?  assign to 'error' instead?

> pwd
/lnx/src/NEXT/linux-next-20101217

> quilt ser -v
= kvm-asm-constraint12.patch

> make ARCH=i386 O=X32 all 2>&1 | tee kvm7.out
<kconfig messages deleted>
  Using /lnx/src/NEXT/linux-next-20101217 as source for kernel
  GEN     /lnx/src/NEXT/linux-next-20101217/X32/Makefile
  CHK     include/linux/version.h
  CHK     include/generated/utsrelease.h
  CALL    /lnx/src/NEXT/linux-next-20101217/scripts/checksyscalls.sh
  CHK     include/generated/compile.h
  CC      arch/x86/kvm/vmx.o
/lnx/src/NEXT/linux-next-20101217/arch/x86/kvm/vmx.c: Assembler messages:
/lnx/src/NEXT/linux-next-20101217/arch/x86/kvm/vmx.c:488: Error: bad register name `%sil'
make[3]: *** [arch/x86/kvm/vmx.o] Error 1
make[2]: *** [arch/x86/kvm] Error 2
make[1]: *** [arch/x86] Error 2
make: *** [sub-make] Error 2


This is with the entire function being empty (no code, no data).

> Wierd.

Definitely.  I can't explain it.

-- 
~Randy
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