From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NCwXE-0004e5-79 for qemu-devel@nongnu.org; Tue, 24 Nov 2009 09:38:28 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1NCwX9-0004Zz-3T for qemu-devel@nongnu.org; Tue, 24 Nov 2009 09:38:27 -0500 Received: from [199.232.76.173] (port=55778 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NCwX8-0004Zq-Ii for qemu-devel@nongnu.org; Tue, 24 Nov 2009 09:38:22 -0500 Received: from mail2.shareable.org ([80.68.89.115]:50767) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NCwX8-0005IK-42 for qemu-devel@nongnu.org; Tue, 24 Nov 2009 09:38:22 -0500 Date: Tue, 24 Nov 2009 14:38:12 +0000 From: Jamie Lokier Subject: Re: [Qemu-devel] Re: POST failure (loop) with isapc and seabios Message-ID: <20091124143812.GA27783@shareable.org> References: <20091122151052.GK3193@redhat.com> <217FD12D88EA4AC2B2A32D77E010B16C@FSCPC> <20091122153809.GL3193@redhat.com> <8A56C1F849F34911ABF51DE049CA3D24@FSCPC> <20091123111137.GF2999@redhat.com> <11090DAABE9449F7B5D1415C45F8F411@FSCPC> <20091123194307.GC13854@redhat.com> <2D659FA33BF64C419243FD76049AFD33@FSCPC> <20091124062810.GZ2999@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20091124062810.GZ2999@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: Kevin O'Connor , qemu-devel@nongnu.org, Sebastian Herbszt Gleb Natapov wrote: > On Mon, Nov 23, 2009 at 10:30:56PM +0100, Sebastian Herbszt wrote: > > Gleb Natapov wrote: > > >On Mon, Nov 23, 2009 at 08:19:54PM +0100, Sebastian Herbszt wrote: > > >>Gleb Natapov wrote: > > >>>On Sun, Nov 22, 2009 at 09:01:45PM +0100, Sebastian Herbszt wrote: > > >>>>Gleb Natapov wrote: > > >>>>>On Sun, Nov 22, 2009 at 04:31:24PM +0100, Sebastian Herbszt wrote: > > >>>>>> > > >>>>>>Bad things could happen if someone modifies the BIOS because it's unprotected > > >>>>>>(e.g. VM crash). > > >>>>>> > > >>>>>BIOS is reloaded during VM reset. > > >>>> > > >>>>The BIOS is not reloaded - tested with "reboot" on Linux and system_reset in monitor. > > >>>> > > >>>Looks like a bug. Tested with latest QEMU version I assume? > > >> > > >>Tested with v0.11.0-rc0-1677-gf165b53. Where do you suspect a bug? In the behaviour > > >>on "reboot" or system_reset? I think it depends wheter it's a software or hardware reset. > > >> > > >The bug is that BIOS rom is not reloaded on hardware reset (what do you > > >call software reset?). Can you retest with latest git? > > > > Same with v0.11.0-rc0-1699-gb0293e5. > > Bochs has the notion of BX_RESET_SOFTWARE and BX_RESET_HARDWARE. Those > > two describe the source of the reset and the hardware, in most cases just the cpu, is reset > > differently depending on the source (e.g. hardware reset / power on vs. INIT#). I think this > > behaviour is also described in the 440fx spec (chapter "4.5.3 SYSTEM RESET"). > > > > If the monitor command "system_reset" is supposed to be the equivalent of pushing the reset > > button of the box, then the bios should be reloaded (i think, not entirely sure what the pin is > > wired to). But the bios should not be reloaded if the OS just jumps to the bios reset code. > > > Correct, but modern OSes never jump to the bios reset code. They use > ACPI reset, kbd reset or triple fault to do reset. All of those generate > exactly the same kind of reset as "system_reset" monitor command. Modern OSes don't (though Linux still has the option reboot=bios which jumps to the BIOS reset code, because that's needed on some PCs!). But QEMU is used to run old OSes too. -- Jamie