Re: kern/60426 (Signal handler corrupts AVX (YMM) registers)

["Robert Elz via gnats" <gnats-admin%NetBSD.org@localhost>]

The following reply was made to PR kern/60426; it has been noted by GNATS.

From: Robert Elz <kre%munnari.OZ.AU@localhost>
To: Taylor R Campbell <riastradh%NetBSD.org@localhost>
Cc: gnats-bugs%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost, bsiegert%netbsd.org@localhost,
        martin%netbsd.org@localhost
Subject: Re: kern/60426 (Signal handler corrupts AVX (YMM) registers)
Date: Thu, 09 Jul 2026 18:35:56 +0700

     Date:        Thu, 9 Jul 2026 10:29:18 +0000
     From:        Taylor R Campbell <riastradh%NetBSD.org@localhost>
     Message-ID:  <20260709102920.640E184DAC%mail.netbsd.org@localhost>
 
 
   | The xmm registers, which have always been available on amd64 since the
   | beginning, are aliases for the low halves of the ymm registers.  Any
   | SSE2 instruction (again: available on amd64 since the beginning)
   | writing to xmmN will generally zero the high half of ymmN as a side
   | effect.
 
 Ugh.   OK - I know zero about the architecture, I am still fuming that
 IBM picked the 8080 when the NetSemi equiv (the identity of which I have
 forgotten) was so much nicer.   Even the z80 was (slightly) better.
 I assume that so few people wanted 8080s (in quantity) that they got
 a good deal...
 
 That however sounds like yet another horrid Intel design choice.
 
 kre