On Fri, Mar 11, 2016 at 02:23:31PM +0100, Ladi Prosek wrote: > On Fri, Mar 11, 2016 at 2:09 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > > On Fri, Mar 11, 2016 at 02:43:23AM +0200, Michael S. Tsirkin wrote: > >> On Thu, Mar 10, 2016 at 04:04:31PM +0100, Ladi Prosek wrote: > >> > On Thu, Mar 10, 2016 at 3:12 PM, Michael S. Tsirkin <m...@redhat.com> > >> > wrote: > >> > > On Wed, Mar 09, 2016 at 07:20:03PM +0100, Ladi Prosek wrote: > >> > >> + /* Enable PCI bus master and reset NIC */ > >> > >> + adjust_pci_device ( pci ); > >> > > > >> > > At the moment, this enables memory and io unconditionally. But I think > >> > > it should check BAR is assigned before enabling and using it, since > >> > > e.g. pci express devices might not have their BARs assigned. > >> > > > >> > > I'm also not sure 64 bit BAR values will work under ipxe - > >> > > if not it's preferably to fall back on io or cfg access. > >> > > >> > Hmm.. 64-bit BARs are indeed not supported. It would be better to > >> > always use the cfg cap then and remove all that BAR mapping business. > >> > Less code and fewer assumptions for the win. > >> > >> Much slower though. > > > > Thinking more about it, I think it's a good idea to > > leave the mapping infrastructure in place, but > > maybe only do the CFG approach as the first step. > > > > Once code is upstream and works, we can add > > faster BAR/IO support later. > > Apologies for a naive question: since we need a 64-bit iPXE build for > proper 64-bit BAR support, does it mean that we would have to ship two > .rom files with QEMU, one for 32-bit guests and one for 64-bit guests?
Right - how does one handle 32 bit guests? Maybe include both binaries in the rom, and add a wrapper selecting the correct part of the ROM depending on the CPU? 1. start wrapper 2. check cpuid for 64 bit extensions 3. run 32 or 64 bit binary A bit wasteful but rather easy to implement. Did anyone try anything like this? > > Cc Gerd who worked on similar issues for virtio blk. > > > > Gerd, what did you do there? > > > >> > > -- > >> > > MST _______________________________________________ ipxe-devel mailing list ipxe-devel@lists.ipxe.org https://lists.ipxe.org/mailman/listinfo.cgi/ipxe-devel
