From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: booting from virtio-blk Date: Tue, 01 Apr 2008 12:09:33 -0500 Message-ID: <47F26C4D.1090406@us.ibm.com> References: <1207051275240-git-send-email-ehrhardt@linux.vnet.ibm.com> <47F225D2.9020409@linux.vnet.ibm.com> <1207060430.6214.12.camel@basalt> <47F24ABA.3020404@us.ibm.com> <1207066432.6214.29.camel@basalt> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: kvm-ppc-devel@lists.sourceforge.net, Christian Ehrhardt , Rusty Russell , kvm-devel To: Hollis Blanchard Return-path: In-Reply-To: <1207066432.6214.29.camel@basalt> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces@lists.sourceforge.net Errors-To: kvm-devel-bounces@lists.sourceforge.net List-Id: kvm.vger.kernel.org Hollis Blanchard wrote: > > Thanks Anthony, you've saved me a lot of debug time! Rusty, doing 64-bit > PCI config space accesses with ioread8() definitely violates the > principle of least surprises, and would have taken me a long time to > track down. :( > It's the unfortunate side-effect of using PCI config space without passing it's semantics through to the virtio devices. Right now, you do a config_get which is basically a memcpy. If we didn't do accesses with ioread8(), you could potentially have a caller than did a config_get() of size 4 that didn't intend on having endian conversion applied. The other option would have been to provide config_get() and config_get8/16/32/64() the later performing endian conversion. Regards, Anthony Liguori > Attached is a boot log of a PowerPC guest booting from virtio-blk root. > > "ramdisk_image" is the standard ~4MB image provided with DENX Embedded > Linux Development Kit. Booting is also *way* faster than NFS root (a few > seconds to get to a shell :) . > > ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://ad.doubleclick.net/clk;164216239;13503038;w?http://sf.net/marketplace