X-Authentication-Warning: delorie.com: mail set sender to djgpp-bounces using -f
From: Rugxulo <rugxulo AT gmail DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Please help resurrecting GDB for version 7.0 release
Date: Mon, 4 May 2009 22:33:20 -0700 (PDT)
Organization: http://groups.google.com
Lines: 28
Message-ID: <0ac86821-b47c-4b2d-b7f5-6c60a12986c3@n4g2000vba.googlegroups.com>
References: <83zldveryw DOT fsf AT gnu DOT org> <684bdd55-b464-4e61-b28e-28774dc6ced8 AT o27g2000vbd DOT googlegroups DOT com> 
	<83y6tfem02 DOT fsf AT gnu DOT org> <_ZKdnV74euw2-2HUnZ2dnUVZ_uednZ2d AT earthlink DOT com> 
	<83ws8zeb05 DOT fsf AT gnu DOT org> <Z4adna6AJcyQeWDUnZ2dnUVZ_t-dnZ2d AT earthlink DOT com> 
	<d5126d62-422a-4cdd-989e-96fa0f99359a AT h23g2000vbc DOT googlegroups DOT com> 
	<83skjldt35 DOT fsf AT gnu DOT org> <58b10f6a-eba5-4cc2-bef8-cc5fc4251e06 AT q2g2000vbr DOT googlegroups DOT com> 
	<83fxfkdz2n DOT fsf AT gnu DOT org> <000b187c-f14b-4f37-81ca-0d93f4e1b2e1 AT g20g2000vba DOT googlegroups DOT com> 
	<322b2e53-eb4a-4770-a039-e4dfe6af8bb7 AT r34g2000vbi DOT googlegroups DOT com>
NNTP-Posting-Host: 65.13.115.246
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
X-Trace: posting.google.com 1241501600 32473 127.0.0.1 (5 May 2009 05:33:20 GMT)
X-Complaints-To: groups-abuse AT google DOT com
NNTP-Posting-Date: Tue, 5 May 2009 05:33:20 +0000 (UTC)
Complaints-To: groups-abuse AT google DOT com
Injection-Info: n4g2000vba.googlegroups.com; posting-host=65.13.115.246; 
	posting-account=p5rsXQoAAAB8KPnVlgg9E_vlm2dvVhfO
User-Agent: G2/1.0
X-HTTP-UserAgent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-US; rv:1.9.0.10) 
	Gecko/2009042316 Firefox/3.0.10 (.NET CLR 3.5.30729),gzip(gfe),gzip(gfe)
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp
Reply-To: djgpp AT delorie DOT com

Hi yet again,


On May 5, 12:28=A0am, Rugxulo <rugx DOT  DOT  DOT  AT gmail DOT com> wrote:
>
> On May 5, 12:08=A0am, Rugxulo <rugx DOT  DOT  DOT  AT gmail DOT com> wrote:
>
> > On May 4, 10:10=A0pm, Eli Zaretskii <e DOT  DOT  DOT  AT gnu DOT org> wrote:
>
> > In other words, I would've thought you could do the following in ring
> > 3, but apparently not:
>
> > =A0 mov eax,cr4 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0; (CR4 first introduced =
in Pentium)
> > =A0 bt eax,OSFXSR =A0 =A0 =A0 =A0 =A0 =A0 =A0; if already set, no need =
to enable
> > =A0 jc .bye
>
> And yet I just tested again on Vista (since the above was from
> memory), and it seems to work! So either I tested wrong, got confused,
> or it's a bug in XP (which I can't test at the moment), most likely
> one of the former. Fun fun fun. =A0 :-P

And by "seems to work", I mean it doesn't cause an exception. Stepping
through with GDB (and yes, I used "volatile" just in case) shows that
EAX is 0 after the move, so that's not helpful at all. Must be
virtualized in ring 3 like eflags is, in other words not reliable at
all.