Re: [libvirt] OVMF exposure in libvirt

On 14.07.2014 16:12, Paolo Bonzini wrote: > Il 14/07/2014 11:27, Daniel P. Berrange ha scritto: >> -drive file=img_1,if=pflash,format=raw,readonly \ >> -drive file=img_2,if=pflash,format=raw > > It's safer to add ",unit=0" and ",unit=1" too. > >> We already use <loader/> for specifying alternative BIOS blobs for >> the QEMU -bios arg. Since you say this obsoletes the -bios arg, I >> think it makes sense to use <loader/> for the read-only firmware >> image. > > It obsoletes the -bios argument, but it is not the same thing: > > 1) on some machines you can use "-drive if=pflash" for the nvram, but > not for the firmware And how should the FW cmd line look like then?

> > 2) on some older versions of QEMU, "-drive if=pflash" will work only on > TCG or will not work at all so you cannot blindly replace it. Whoa. How to detect this? I mean, how do detect both?

> > What about: > > <loader readonly='on|off' type='rom|flash'>...</loader> > <nvram>...</nvram> > > where the mapping from <nvram> to -drive if=flash is partly > machine-dependent. On x86, for example, <nvram> adds the ",unit=1" > sub-option and fails if the <loader> element is absent; it also fails if > <loader> has type='rom'. > Makes sense. >> For the variable storage, I'd probably suggest <nvram/> as the >> element name, since IIUC that's a fairly commonly used term for >> this concept. > > I like this. > >> Additionally it would be great if we'd be able to >> generate an empty nvram for a guest if the user doesn't specify it. I'm not big fan of this. Pre-creating storage is something that should be done by mgmt applications (migration with non-shared storage is something different). > > Laszlo has OVMF patches to "auto-format" an all-zero nvram file. Great. Do they work automagically or does libvirt need to enable the formatting somehow (e.g. monitor command, cmd line argument, ...)? > > Paolo