On 11/07/2015 08:29 AM, Mark Cave-Ayland wrote: > Whilst testing various images under qemu-system-sparc64, I've noticed a > regression with the new NetBSD 7 release. On boot the kernel hangs just > after detecting the CDROM and eventually outputs "cmdide0:1:0: lost > interrupt" onto the console. > > A quick session with git bisect points to the following patch: > > 9ef2e93f9b1888c7d0deb4a105149138e6ad2e98 is the first bad commit > commit 9ef2e93f9b1888c7d0deb4a105149138e6ad2e98 > Author: John Snow <js...@redhat.com> > Date: Thu Sep 17 14:17:05 2015 -0400 > > atapi: abort transfers with 0 byte limits > > We're supposed to abort on transfers like this, unless we fill > Word 125 of our IDENTIFY data with a default transfer size, which > we don't currently do. > > This is an ATA error, not a SCSI/ATAPI one. > See ATA8-ACS3 sections 7.17.6.49 or 7.21.5. > > If we don't do this, QEMU will loop forever trying to transfer > zero bytes, which isn't particularly useful. > > Signed-off-by: John Snow <js...@redhat.com> > Reviewed-by: Markus Armbruster <arm...@redhat.com> > Message-id: 1442253685-23349-2-git-send-email-js...@redhat.com > > Reproducing the bug is easy enough using the command line below: > > ./qemu-system-sparc64 -cdrom NetBSD-7.0-sparc64.iso -boot d -nographic > > Testing also shows that NetBSD 6 is apparently unaffected by this change. > > > ATB, > > Mark. >
Well, that's interesting ... The condition this patch was added to protect was PIO transfers with 0 byte transfer limits, which caused an infinite loop before. (It shouldn't have ever worked!) That I actually managed to break a guest with this is a little shocking. I'll debug, thanks. --js
