[Qemu-devel] PCI CAS implementation in qemu

[Qemu-devel] PCI CAS implementation in qemu

[Francois WELLENREITER]

Hi there,

I order to develop a qemu module, I aim to use the PCI CAS (compare and 
swap) function
to guarantee an atomic access somewhere in the guest memory (in a 
multi-core emulation case).

Nevertheless, I did not find any routine in qemu implementing this function.

Could anyone on this list tell me if this is implemented and if that's 
not the case, if this would be hard to get implemented ?

Thanks in advance for any answer.

Regards,

                     François

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François WELLENREITER
Bull - R&D Extreme Computing - Grenoble
francois.wellenreiter@bull.net

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Re: [Qemu-devel] PCI CAS implementation in qemu

[Paolo Bonzini]

Il 20/11/2012 17:32, Francois WELLENREITER ha scritto:
> 
> I order to develop a qemu module, I aim to use the PCI CAS (compare
> and swap) function to guarantee an atomic access somewhere in the
> guest memory (in a multi-core emulation case).
> 
> Nevertheless, I did not find any routine in qemu implementing this
> function.
> 
> Could anyone on this list tell me if this is implemented and if that's
> not the case, if this would be hard to get implemented ?

(I know nothing about PCI CAS).

Can you just use a compare-and-swap in the QEMU device model (via
__sync_val_compare_and_swap for example)?

Paolo