Re: [PATCH] add xfloat thread state interface

[Samuel Thibault]

Hello,

Luca Dariz, le lun. 05 août 2024 14:52:24 +0200, a ecrit:
> Il 05/08/24 00:32, Samuel Thibault ha scritto:
> > Luca Dariz, le ven. 02 août 2024 17:32:34 +0200, a ecrit:
> > > +#define XFP_STATE_BYTES (sizeof (struct i386_xfp_save))
> > 
> > That is not sufficient: depending on the sse level and the saving style,
> > we have various amount of data to store. See fp_xsave_size computed in
> > init_fpu, we have to save all of that. We thus have to make get_state
> > check that the user-land buffer is large enough for that. And as I
> > mentioned on irc, the i386_xfloat_state stucture should contain the
> > fp_save_kind for glibc to know how to restore it.
> > 
> 
> Right, maybe we also need a way for userspace to discover the required size?
> e.g. with a separate call i386_get_xstate_size().

I was thinking that perhaps glibc can compute it itself with cpuid, but
it'll be simpler to add some call to gnumach indeed.

Samuel