From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20792 invoked by alias); 28 Sep 2012 02:40:02 -0000 Received: (qmail 20734 invoked by uid 22791); 28 Sep 2012 02:40:00 -0000 X-SWARE-Spam-Status: No, hits=-3.3 required=5.0 tests=AWL,BAYES_00,KHOP_THREADED,RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from sibelius.xs4all.nl (HELO glazunov.sibelius.xs4all.nl) (83.163.83.176) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Fri, 28 Sep 2012 02:39:55 +0000 Received: from glazunov.sibelius.xs4all.nl (kettenis@localhost [127.0.0.1]) by glazunov.sibelius.xs4all.nl (8.14.5/8.14.3) with ESMTP id q8S2dghE014317; Fri, 28 Sep 2012 04:39:42 +0200 (CEST) Received: (from kettenis@localhost) by glazunov.sibelius.xs4all.nl (8.14.5/8.14.3/Submit) id q8S2ddal001019; Fri, 28 Sep 2012 04:39:39 +0200 (CEST) Date: Fri, 28 Sep 2012 02:40:00 -0000 Message-Id: <201209280239.q8S2ddal001019@glazunov.sibelius.xs4all.nl> From: Mark Kettenis To: markus.t.metzger@intel.com CC: mark.kettenis@xs4all.nl, gdb-patches@sourceware.org, markus.t.metzger@gmail.com, jan.kratochvil@redhat.com, palves@redhat.com, tromey@redhat.com In-reply-to: (markus.t.metzger@intel.com) Subject: Re: [patch v3 16/16] btrace, x86: restrict to Atom References: <1344949171-9545-1-git-send-email-markus.t.metzger@intel.com> <1344949171-9545-17-git-send-email-markus.t.metzger@intel.com> <201208141327.q7EDR7TC017727@glazunov.sibelius.xs4all.nl> Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2012-09/txt/msg00663.txt.bz2 > From: "Metzger, Markus T" > Date: Mon, 24 Sep 2012 12:22:42 +0000 > > Ping. Native code can only go into -nat.c files. But I still think putting CPU model specific checks anywhere in GDB is wrong. If there are broken kernels out there, figure out a way to detect them. > > -----Original Message----- > > From: Metzger, Markus T > > Sent: Tuesday, August 14, 2012 3:42 PM > > To: Mark Kettenis > > Cc: gdb-patches@sourceware.org; markus.t.metzger@gmail.com; jan.kratochvil@redhat.com; palves@redhat.com; > > tromey@redhat.com > > Subject: RE: [patch v3 16/16] btrace, x86: restrict to Atom > > > > > -----Original Message----- > > > From: Mark Kettenis [mailto:mark.kettenis@xs4all.nl] > > > Sent: Tuesday, August 14, 2012 3:27 PM > > > > Thanks for your feedback! > > > > > > > > +int > > > > +i386_linux_supports_btrace (void) > > > > +{ > > > > + unsigned int cpuid, model, family; > > > > + > > > > + if (!linux_supports_btrace ()) > > > > + return 0; > > > > + > > > > + __asm__ __volatile__ ("movl $1, %%eax;" > > > > + "cpuid;" > > > > + : "=a" (cpuid) > > > > + :: "%ebx", "%ecx", "%edx"); > > > > + > > > > [...] > > > > > You can't have this function in a -tdep.c, since this file needs to be > > > compilable everywhere (not just on i386/amd64). But even in a -nat.c > > > file you shouldn't use inline assembly, since it isn't a standardized > > > C feature. I can only guess why you want to restrict this feature to > > > Atom only, but I suspect that the proper solution is to query the > > > target whether branch tracing is supported. That means the -nat.c > > > code should have code to query for support in the Linux kernel. > > > > I agree that it would be better to have this check done in the kernel. The problem is that such a patch will take very long before > > it becomes available in distributions. And even then, we would need to handle kernels without the patch, so we would need > > something > > similar to this in gdb, as well. > > > > I took the cpuid bits from gdb/go32-nat.c. I have not seen any compilation guard around it. > > > > I thought that the i386-tdep files are meant to contain i386 specific code, that's why I put the code there. Where would be the > > right place to put such code? > > > > Thanks, > > Markus. > Intel GmbH > Dornacher Strasse 1 > 85622 Feldkirchen/Muenchen, Deutschland > Sitz der Gesellschaft: Feldkirchen bei Muenchen > Geschaeftsfuehrer: Peter Gleissner, Christian Lamprechter, Hannes Schwaderer, Douglas Lusk > Registergericht: Muenchen HRB 47456 > Ust.-IdNr./VAT Registration No.: DE129385895 > Citibank Frankfurt a.M. (BLZ 502 109 00) 600119052 > > >