On Wed, Mar 31, 2010 at 02:24:51PM -0500, Anthony Liguori wrote: > On 03/31/2010 02:07 PM, Michael S. Tsirkin wrote: >> On Wed, Mar 31, 2010 at 03:38:05PM -0300, Luiz Capitulino wrote: >> >>> On Wed, 31 Mar 2010 13:26:23 -0500 >>> Anthony Liguori<anth...@codemonkey.ws> wrote: >>> >>> >>>> On 03/31/2010 01:20 PM, Michael S. Tsirkin wrote: >>>> >>>>> From: David L Stevens<dlstev...@us.ibm.com> >>>>> >>>>> vhost driver in qemu didn't ack features, and this happens >>>>> to work because we don't really require any features. However, >>>>> it's better not to rely on this. This patch passes features to >>>>> vhost as guest acks them. >>>>> >>>>> Signed-off-by: David L Stevens<dlstev...@us.ibm.com> >>>>> Signed-off-by: Michael S. Tsirkin<m...@redhat.com> >>>>> --- >>>>> >>>>> Anthony, here's a fixup patch to address an issue in vhost >>>>> patches. Incidentially, what's the status of the vhost patchset? >>>>> >>>>> >>>> http://repo.or.cz/w/qemu/aliguori-queue.git vhost >>>> >>>> Is what I'm currently testing. With vhost disabled, the following seg >>>> faults: >>>> >>>> qemu-system-x86_64 -hda ~/images/linux.img -net tap -net >>>> nic,model=virtio -enable-kvm >>>> >>>> But not when using TCG. I'm not sure that it's your patches at fault >>>> and I'm attempting to bisect now to figure that out. >>>> >>> Probably this is the same segfault I'm getting right now in master, >>> bisect says it's: >>> >>> """ >>> commit ad96090a01d848df67d70c5259ed8aa321fa8716 >>> Author: Blue Swirl<blauwir...@gmail.com> >>> Date: Mon Mar 29 19:23:52 2010 +0000 >>> >>> Refactor target specific handling, compile vl.c only once >>> """ >>> >> Why are the compile once patches helpful? They seem to introduce >> churn and bugs, they actively make it harder to extend qemu as you can't use >> target-specific code in code that is compiled once, they might have >> performance penalty - and what do we gain? Any given user is unlikely to >> need to build on more than one target, distros have enough computing >> power to build in parallel. >> >> Maybe it makes sense to revert the compile once patches, and discuss >> these issues before re-commit? >> > > Compiling objects once is certainly useful. Long term, I think most of > us want to see a single qemu executable that works for all architectures > and compiling once is an important step in that direction. >
While it probably make sense to achieve this goal, it doesn't mean it should be done the dirty way. For example it is known for a lot of time that the solution for the bswap in the device code is to add a bus model doing the byteswapping. Removing the #ifdef by deciding "this device will only be big/little endian" doesn't seem to go in the right direction. -- Aurelien Jarno GPG: 1024D/F1BCDB73 aurel...@aurel32.net http://www.aurel32.net
