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SubjectRe: [PATCH RFC WIP] x86/paravirt: add register-saving thunks to reduce caller register pressure
Pavel Machek wrote:
>> This patch seeks to alleviate this pressure by introducing wrapper
>> thunks that will do the register saving/restoring, so that the
>> callsite doesn't need to worry about it, but the callee function can
>> be conventional compiler-generated code. In many cases (particularly
>> performance-sensitive cases) the callee will be in assembler anyway,
>> and need not use the compiler's calling convention.
>>
>> Standard calling convention is:
>> arguments return scratch
>> x86-32 eax edx ecx eax ?
>>
>
> esi edi ebp ?
>

Those are callee-save, so the caller doesn't need to worry about
preserving their values.

> actually standard calling convention is all arguments on stack iirc
> but we use regparm=3 for kernel...?
>

Yes. "standard" = "standard kernel calling convention"


J


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