From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:52948) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UouG4-0007KY-9r for qemu-devel@nongnu.org; Tue, 18 Jun 2013 07:39:33 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UouG2-0000SA-Cf for qemu-devel@nongnu.org; Tue, 18 Jun 2013 07:39:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:29267) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UouG2-0000Rm-4w for qemu-devel@nongnu.org; Tue, 18 Jun 2013 07:39:30 -0400 From: Markus Armbruster References: <1371208516-7857-1-git-send-email-armbru@redhat.com> <1371208516-7857-6-git-send-email-armbru@redhat.com> <87ppvog69o.fsf@codemonkey.ws> Date: Tue, 18 Jun 2013 13:39:25 +0200 In-Reply-To: <87ppvog69o.fsf@codemonkey.ws> (Anthony Liguori's message of "Fri, 14 Jun 2013 08:40:19 -0500") Message-ID: <87ppvjodg2.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain Subject: Re: [Qemu-devel] [PATCH v3 05/16] pc: Make -no-fd-bootchk stick across boot order changes List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: aviksil@linux.vnet.ibm.com, alex.williamson@redhat.com, jan.kiszka@siemens.com, qemu-devel@nongnu.org, afaerber@suse.de Anthony Liguori writes: > Markus Armbruster writes: > >> Option -no-fd-bootchk asks the BIOS to attempt booting from a floppy >> even when the boot sector signature isn't there, by setting a bit in >> RTC CMOS. It was added back in 2006 (commit 52ca8d6a). >> >> Two years later, commit 0ecdffbb added monitor command boot_set. >> Implemented by new function pc_boot_set(). It unconditionally clears >> the floppy signature bit in CMOS. >> >> Commit e0f084bf added -boot option once to automatically change the >> boot order on first reset. Reuses pc_boot_set(), thus also clears the >> floppy signature bit. Commit d9346e81 took care to preserve this >> behavior. > > Quite a history there :-) > > Does anyone still use no-fd-bootchk? No idea. > Do you know what the original > use-case was? Its commit message is of no help. Best we got is the option documentation: Disable boot signature checking for floppy disks in Bochs BIOS. It may be needed to boot from old floppy disks. As far as I can tell, SeaBIOS implements this, too. >> Thus, -no-fd-bootchk applies to any number of boots. Except it >> applies just to the first boot with -boot once, and never after >> boot_set. Weird. Make it stick instead: set the bit according to >> -no-fd-bootchk in pc_boot_set(). >> >> Signed-off-by: Markus Armbruster > > Reviewed-by: Anthony Liguori Thanks!