Re: [Xen-devel] [PATCH] x86: usercopy assembly constraints

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 13/11/07 20:20, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:

> On 13/11/07 16:02, "Jan Beulich" <jbeulich@xxxxxxxxxx> wrote:
> 
>> Besides only being correct this way, this helps work around a gcc 4.3
>> issue.
>> At the same time, add some white space, re-order the inputs, and remove
>> a bogus cast.
> 
> What's the bug? Does some gcc allocate the 4th output parameter into one of
> the other used registers (cx,si,di) if we don't use '=&'?

If this is the case, it sounds to me like a gcc bug (allocating two outputs
into the same register) and it could potentially hit on a number of our
other asm statements I'm pretty sure.

 -- Keir



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