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Re: RFC: Should x86-64 support arbitrary calling conventions?
On Fri, Mar 24, 2017 at 12:43 PM, Florian Weimer <fw@deneb.enyo.de> wrote:
>>> I think the main benefit is that we don't have to adjust the dynamic
>>> linker trampoline for each new microarchitecture, and applications can
>>> safely start using new CPU features once the kernel indicates support.
>>
>> That is true.
>
> I think this alone is sufficient value to make this change.
>
> What do others think?
I still want to know why the dynamic linker trampoline has to do this
in the first place. Why can't we "simply" avoid touching the
floating-point and vector registers at all? Like how the kernel
mostly restricts itself to integer instructions.
(Come to think of it, saving and restoring these registers will
vitiate the context switch optimizations for programs that only need
the integer registers.)
zw