Re: kern/50332: AVX instructions don't work but OSXSAVE flag is set

[tg%gmplib.org@localhost (Torbjörn Granlund)]

The following reply was made to PR kern/50332; it has been noted by GNATS.

From: tg%gmplib.org@localhost (=?utf-8?Q?Torbj=C3=B6rn?= Granlund)
To: gnats-bugs%NetBSD.org@localhost
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost, netbsd-bugs%netbsd.org@localhost
Subject: Re: kern/50332: AVX instructions don't work but OSXSAVE flag is set
Date: Tue, 20 Oct 2015 18:41:54 +0200

 David Laight <david%l8s.co.uk@localhost> writes:
 
    No, there is no reason why you can't have a cpu (and os) that supports x=
 save
    (etc) but doesn't support avx.
    You have to look at the bitmap of supported extensions.
    IIRC Only the x87 fpu registers are mandatory.
 =20=20=20
 Note that my updated test case tests both flags to make this a moot
 point.
 
    However that probably isn't the issue here.
    More likely is that something in xen should stop avx being used,
    or xen needs to do something different from bare-metal to support avx.
 =20=20=20
 Please note that non-NetBSD guest systems have no problem.  Also, NetBSD
 with no Xen around works fine.
 
 That makes me suspect Xen is innocent and that NetBSD gets this wrong
 when run with Xen.
 
 My complaint is not that AVX does not work under Xen+NetBSD, but that it
 doesn't work in spite of that NetBSD sets OSXSAVE.
 
 --=20
 Torbj=C3=B6rn
 Please encrypt, key id 0xC8601622