Paravirt compile failure with gcc33

Paravirt compile failure with gcc33

[Jan Engelhardt]

Hi,


As I was compile-testing 2.6.33-rc with gcc-3.3,
binutils-2.19.51-10.26.4.x86_64, I observed a failure when 
CONFIG_PARAVIRT is turned on:


[any file]
/home/jengelh/code/linux/arch/x86/include/asm/paravirt.h: In function 
`rif_seq_stop':
/home/jengelh/code/linux/arch/x86/include/asm/paravirt.h:763: warning: 
asm operand 5 probably doesn't match constraints
/home/jengelh/code/linux/arch/x86/include/asm/paravirt.h:858: warning: 
asm operand 2 probably doesn't match constraints
/home/jengelh/code/linux/arch/x86/include/asm/paravirt.h:763: error: 
impossible constraint in `asm'
/home/jengelh/code/linux/arch/x86/include/asm/paravirt.h:858: error: 
impossible constraint in `asm'

Disabling either PARAVIRT or using GCC4.x works around this.

Re: Paravirt compile failure with gcc33

[Jeremy Fitzhardinge]

On 02/10/2010 10:13 AM, Jan Engelhardt wrote:
> As I was compile-testing 2.6.33-rc with gcc-3.3,
> binutils-2.19.51-10.26.4.x86_64, I observed a failure when
> CONFIG_PARAVIRT is turned on:
>    

Yeah, there's a gcc bug of some kind there, and its very hard to see how 
to work around it.  When we last discussed this, I think we were close 
to deciding to obsolete gcc 3.3.

HPA, do you remember?

     J

>
> [any file]
> /home/jengelh/code/linux/arch/x86/include/asm/paravirt.h: In function
> `rif_seq_stop':
> /home/jengelh/code/linux/arch/x86/include/asm/paravirt.h:763: warning:
> asm operand 5 probably doesn't match constraints
> /home/jengelh/code/linux/arch/x86/include/asm/paravirt.h:858: warning:
> asm operand 2 probably doesn't match constraints
> /home/jengelh/code/linux/arch/x86/include/asm/paravirt.h:763: error:
> impossible constraint in `asm'
> /home/jengelh/code/linux/arch/x86/include/asm/paravirt.h:858: error:
> impossible constraint in `asm'
>
> Disabling either PARAVIRT or using GCC4.x works around this.
> _______________________________________________
> Virtualization mailing list
> Virtualization@lists.linux-foundation.org
> https://lists.linux-foundation.org/mailman/listinfo/virtualization
>
>    

Re: Paravirt compile failure with gcc33

[H. Peter Anvin]

On 02/10/2010 10:38 AM, Jeremy Fitzhardinge wrote:
> On 02/10/2010 10:13 AM, Jan Engelhardt wrote:
>> As I was compile-testing 2.6.33-rc with gcc-3.3,
>> binutils-2.19.51-10.26.4.x86_64, I observed a failure when
>> CONFIG_PARAVIRT is turned on:
>>    
> 
> Yeah, there's a gcc bug of some kind there, and its very hard to see how 
> to work around it.  When we last discussed this, I think we were close 
> to deciding to obsolete gcc 3.3.
> 
> HPA, do you remember?
> 

I don't, and the macros are tangled enough that I'm not actually sure
what the failure really is.

	-hpa

Re: Paravirt compile failure with gcc33

[Jan Engelhardt]

On Wednesday 2010-02-10 19:38, Jeremy Fitzhardinge wrote:

> On 02/10/2010 10:13 AM, Jan Engelhardt wrote:
>> As I was compile-testing 2.6.33-rc with gcc-3.3,
>> binutils-2.19.51-10.26.4.x86_64, I observed a failure when
>> CONFIG_PARAVIRT is turned on:
>>   
>
> Yeah, there's a gcc bug of some kind there, and its very hard to see how to
> work around it.  When we last discussed this, I think we were close to deciding
> to obsolete gcc 3.3.
>
> HPA, do you remember?

In fact, there's such a big bug in there that I'll get a runaway 
allocation later on when kvm.o is to be compiled. This is getting fun,
but I am absolutely fine with obsoleting 3.x  :)

Re: Paravirt compile failure with gcc33

[H. Peter Anvin]

On 02/10/2010 11:20 AM, Jan Engelhardt wrote:
> On Wednesday 2010-02-10 19:38, Jeremy Fitzhardinge wrote:
> 
>> On 02/10/2010 10:13 AM, Jan Engelhardt wrote:
>>> As I was compile-testing 2.6.33-rc with gcc-3.3,
>>> binutils-2.19.51-10.26.4.x86_64, I observed a failure when
>>> CONFIG_PARAVIRT is turned on:
>>>   
>>
>> Yeah, there's a gcc bug of some kind there, and its very hard to see how to
>> work around it.  When we last discussed this, I think we were close to deciding
>> to obsolete gcc 3.3.
>>
>> HPA, do you remember?
> 
> In fact, there's such a big bug in there that I'll get a runaway 
> allocation later on when kvm.o is to be compiled. This is getting fun,
> but I am absolutely fine with obsoleting 3.x  :)

I have heard of some people using 3.4, but I'm not sure if anyone cares
for current kernels and for x86, in particular.  Some other
architectures might still be stuck on 3.x.

For x86 in particular 3.x support is becoming more of a headache than a
help.

	-hpa