Re: Re-enabling xsave

[John Nemeth <jnemeth%cue.bc.ca@localhost>]

On Nov 8,  5:16pm, Maxime Villard wrote:
} Le 07/11/2017 à 21:06, coypu%sdf.org@localhost a écrit :
} >   Index: identcpu.c
} >   ===================================================================
} >   RCS file: /cvsroot/src/sys/arch/x86/x86/identcpu.c,v
} >   retrieving revision 1.64
} >   diff -u -r1.64 identcpu.c
} >   --- identcpu.c	3 Nov 2017 16:21:01 -0000	1.64
} >   +++ identcpu.c	5 Nov 2017 17:11:12 -0000
} >   @@ -771,12 +771,7 @@
} >    	if (descs[2] > 512)
} >    		x86_fpu_save_size = descs[2];
} >    
} >   -#ifdef XEN
} >   -	/* Don't use xsave, force fxsave with x86_xsave_features = 0. */
} >   -	x86_fpu_save = FPU_SAVE_FXSAVE;
} >   -#else
} >    	x86_xsave_features = (uint64_t)descs[3] << 32 | descs[0];
} >   -#endif
} >    }
} >    
} >    void
} > 
} 
} this can't work as-is, you also need to set bits in cr4 and xcr0, and fix
} mxcsr_mask

     What do you mean that this can't work as is?  You don't exactly
provide much detail.  The code fragment above has been in place
for more then three years.  It's purpose is to stop Xen domUs from
crashing.  It certianly accomplished that goal and there have been
no complaints, of which I know about, in the mean time.  What coypu
wants to do is to revert it to what it looked like prior to 1.46,
which of course, would break things.

}-- End of excerpt from Maxime Villard