Re: Bug#544145: [Xen-devel] Crash with paravirt-ops 2.6.31.6 kernel

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 11/23/09 09:23, Bastian Blank wrote:
>> I don't believe that is the case (the processor would have to carry some
>> state for the entire duration of a syscall for it to make any
>> difference). I think the spec simply assumes that an OS author would
>> want to use sysret if they used syscall.
>>     
> Well, it is documented this way. If you ignore it, it can work (and does
> in this case) but is undefined behaviour.
>   

Linux freely uses iret to return from syscall for things like fork and
exec.  They are complimentary instructions, but nothing requires them to
be paired.

    J

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