From owner-freebsd-emulation@FreeBSD.ORG Tue Feb 11 22:35:03 2014 Return-Path: Delivered-To: freebsd-emulation@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 292F2E3D for ; Tue, 11 Feb 2014 22:35:03 +0000 (UTC) Received: from anubis.delphij.net (anubis.delphij.net [64.62.153.212]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 06D881A75 for ; Tue, 11 Feb 2014 22:35:02 +0000 (UTC) Received: from delphij-macbook.local (c-67-188-85-47.hsd1.ca.comcast.net [67.188.85.47]) (using TLSv1 with cipher ECDHE-RSA-AES128-SHA (128/128 bits)) (No client certificate requested) by anubis.delphij.net (Postfix) with ESMTPSA id DA21BD59A; Tue, 11 Feb 2014 14:34:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=delphij.net; s=anubis; t=1392158096; bh=XGBNtjAXitsMoJcOUfYHq794GLg3JaIHbto7pQtX9zA=; h=Date:From:Reply-To:To:CC:Subject:References:In-Reply-To; b=pBX/zmAvtYUBnUd7/7WIHKmtGd2nilfOLmI1/x2900RgAd6yb9KFCh4QdtSF74fyj L2yZxCk2eNA/ylRp+cNMIwHOd7Yf/Nh3I78LlEJsc4U0q93ZBJTM9qEB+4SXf+OGD6 5weh86k4xqVblUE1AHXI7hodttC4aLRAaB7kOjbA= Message-ID: <52FAA591.1030904@delphij.net> Date: Tue, 11 Feb 2014 14:34:57 -0800 From: Xin Li Organization: The FreeBSD Project MIME-Version: 1.0 To: Michael Tokarev , Kevin O'Connor Subject: Re: [Qemu-devel] *BSD kernel crash at boot in qemu with seabios 1.7.4 (bisected) References: <52F0DE0F.40507@msgid.tls.msk.ru> <20140205174406.GA26098@morn.localdomain> <20140206040442.GA5486@morn.localdomain> <52F383C0.4030002@msgid.tls.msk.ru> In-Reply-To: <52F383C0.4030002@msgid.tls.msk.ru> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Daniele Di Proietto , seabios , qemu-devel , freebsd-emulation@freebsd.org, Gerd Hoffmann , Julian Pidancet X-BeenThere: freebsd-emulation@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list Reply-To: d@delphij.net List-Id: Development of Emulators of other operating systems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 11 Feb 2014 22:35:03 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 2/6/14, 4:44 AM, Michael Tokarev wrote: > [Changing subject to reflect reality] > > I don't really understand what it is all about, as I initially > said. But I've been told on freebsd IRC channels to post the issue > to freebsd-emulation list, which I'm Cc'ing now, and if noone > there answers, also to John Baldwin . > > To bring some context back, here are a few pointers: > > http://bugs.debian.org/737142 -- talking about pc-bsd, but it > appears that the prob affects other BSD kernels too > http://thread.gmane.org/gmane.comp.emulators.qemu/254074 -- this > thread > http://lists.gnu.org/archive/html/qemu-stable/2013-03/msg00037.html > - a weird issue with freebsd reported last december > > If it's a bug in *BSD kernels, maybe someone there will be glad to > fix it. And maybe together we can come out with a more elegant > solution to this issue, or maybe to confirm (or deny) that the > proposed patch is a right thing to do. Yes it does look like a bug in FreeBSD kernel. Is there a PR already or should I create one and assign to myself? I will try to fix this when I have some free cycles. I assume this also happens when running FreeBSD under qemu on FreeBSD, right? Cheers, > Thanks, > > /mjt > > 06.02.2014 08:04, Kevin O'Connor wrote: >> On Wed, Feb 05, 2014 at 12:44:06PM -0500, Kevin O'Connor wrote: >>> On Tue, Feb 04, 2014 at 04:33:19PM +0400, Michael Tokarev >>> wrote: >>>> We have a bugreport in debian, >>>> http://bugs.debian.org/737142, stating that PC-BSD does not >>>> work with seabios-1.7.4 anymore. >>>> >>>> I digged in, and found out that it fails only with -vga std >>>> (cirrus works fine). So I bisected the issue - only >>>> changing vgabios-stdvga.bin, and found this: >> [...] >>> This seems to be similar to the freebsd problem reported last >>> year - see: >>> http://lists.gnu.org/archive/html/qemu-stable/2013-03/msg00037.html >> >>> [...] >>> (*) The best I can think of is to try and construct some hand >>> crafted assembler that can catch buggy x86emu emulators and >>> force a failure.. >> >> I have put together some assember to try and run-time test for >> known broken versions of x86emu. This patch to SeaVGABIOS does >> seem to catch the freebsd issue and in my tests it convinces >> freebsd to take a different approach. The patch is a bit ugly >> though. >> >> Comments welcome. -Kevin >> >> >> commit e3caa553e940efb6184b30a5637134c4aa9f8b65 Author: Kevin >> O'Connor Date: Wed Feb 5 22:47:29 2014 >> -0500 >> >> vgabios: Attempt to detect old x86emu and force a fault. >> >> Check for cases where the leal instruction does not work. This >> instruction is known to not be emulated properly on old versions >> of x86emu. If a broken version of x86emu is found, force a fault >> that x86emu will easily detect. This should help prevent soft >> failures when running old software. >> >> Signed-off-by: Kevin O'Connor >> >> diff --git a/vgasrc/vgaentry.S b/vgasrc/vgaentry.S index >> 9854448..e246e7c 100644 --- a/vgasrc/vgaentry.S +++ >> b/vgasrc/vgaentry.S @@ -45,9 +45,27 @@ _rom_header_signature: * >> Entry points >> ****************************************************************/ >> >> - // This macro is the same as ENTRY_ARG except the >> "calll" - // instruction is avoided to work around known >> issues in the - // emulation of some versions of x86emu. + >> // Force a fault if found to be running on broken x86emu >> versions. + DECLFUNC x86emu_fault +x86emu_fault: + >> int $0x03 +1: hlt + jmp 1b + + // This macro >> implements a call while avoiding instructions + // that >> old versions of x86emu have problems with. + .macro >> VGA_CALLL cfunc + // Make sure leal instruction works. + >> movl $0x8000, %ecx + leal (%ecx, %ecx, 1), %ecx + >> cmpl $0x10000, %ecx + jne x86emu_fault + // Use >> callw instead of calll + push %ax + callw \cfunc + >> .endm + + // This macro is the same as ENTRY_ARG except >> VGA_CALLL is used. .macro ENTRY_ARG_VGA cfunc cli cld @@ -57,7 >> +75,7 @@ _rom_header_signature: movl %esp, %ebx // Backup >> %esp, then zero high bits movzwl %sp, %esp movl %esp, %eax >> // First arg is pointer to struct bregs - pushw %ax ; >> callw \cfunc + VGA_CALLL \cfunc movl %ebx, %esp // >> Restore %esp (including high bits) POPBREGS .endm @@ -103,7 >> +121,7 @@ entry_10_extrastack: movw %ds, %dx // Setup >> %ss/%esp and call function movw %dx, %ss movl %eax, %esp - >> pushw %ax ; callw handle_10 + VGA_CALLL handle_10 >> >> movl %esp, %eax // Restore registers and return movw >> BREGS_size+4(%eax), %ss >> > > _______________________________________________ > freebsd-emulation@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-emulation To > unsubscribe, send any mail to > "freebsd-emulation-unsubscribe@freebsd.org" > -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJS+qWRAAoJEJW2GBstM+nsz3sP/AsGiEPWzHAbQP5nYR9alDiL dmMd8RB4yVYLmJJXCxLldMjNw3kuHRcZ8IrvCaxsFvUHnzdQudmqCc6uxgcWdC3Y gqSYP2/dnG5OXsUqmRHW0yKpfrBlbOA/utRDZz9MzTx4m7sudY8y8ZEUmb2OyJOZ CjQrW5OyHIXUxzdKMlcpiAy5+edQVWk5TBdyz6h0WVrk4A9uuAjOw/DYse05lGVF l1d/Eto+Wui38fMTjfdVJqVcPrfy859aODf/vRkmznujd0Zumr/8OMXmEsF+Q+iv ktRNWab39DXIArMsYbCGr7Xg7Q0ZjZB0eAjB8zxW1a0p/7V4Spf9QQu9wNHVi4sf DOwiaU2K+2/zz/BYIyicyZN+glQMLcq+t3u8uagm6GOcHMx1ZsyFeyIhj8Gbtjfl VUPOVZfu25dogr5GY2U68tPHoiQStsSvdSg4+jaDYK5AZcs1BGZ5i5ncArjATV1Z KIe3ISOzu20BMhjAXHALnTNMFuBWD6+Va6ExVHWkWuz445aQ0REx3hJDqWbm7iVd DTD2N6Bs/uL7P3aVODgz8EqQ6EMhswFYgqSirMb9w38FCLnJ56aAA31kFU00U28p OG8kzgc3dY0II1vVfNLhrJ5kGNDOKxZ62KsXbLHPdBl3cgKweqghd53WTjU/dSo6 0NVfAqheJ3ifZ0I0yB3d =jTIz -----END PGP SIGNATURE-----