On Sun, Nov 6, 2011 at 5:30 AM, Jordan Justen <jljus...@gmail.com> wrote: > Cc: qemu-devel > > On Fri, Nov 4, 2011 at 22:37, Zhi Yong Wu <zwu.ker...@gmail.com> wrote: >> On Sat, Nov 5, 2011 at 12:11 AM, Jordan Justen <jljus...@gmail.com> wrote: >>> On Fri, Nov 4, 2011 at 04:34, Zhi Yong Wu <zwu.ker...@gmail.com> wrote: >>>> BTW: what is the relationship between -bios and -pflash? >>> >>> Previously the QEMU/KVM PC system had no pflash support. You could >>> specify a pflash drive, but it would not appear in the VM. >>> >>> Also, previously the -bios flag would cause the specified binary to be >>> loaded by QEMU, and then it was put into a memory region to be used >>> for the firmware. >>> >>> After this change, the pflash drive is used for firmware. So, it >> This pflash drive is created with -pflash option, right? > > -pflash can be used, but I think it is just a short cut. > > -pflash /path/to/file > is similar to: > -drive if=pflash,file=/path/to/file > > And, after this change, > -bios /path/to/file > is similar to: > -drive if=pflash,file=/path/to/file,readonly=on > >>> should be able to support qcow2, since qemu drives support the >>> different formats. > > I confirmed that you can use a qcow2 image with -bios after this change. > >>> For backward compatibility, this change makes the -bios parameter be >>> another way to specify the pflash drive. If -bios is used, then a >>> read-only pflash drive is created. >> Sorry, i don't fully understand this. How about -bios and -pflash are >> both specified. > > In this case the -pflash will be used, and -bios will be ignored. I > use -bios to create a pflash drive only if no pflash drive exists > already. > > I think this should be okay, since -pflash has no use in the QEMU PC > system before this patch, so it is unlikely that both -pflash and > -bios will be used previously. > >>>> If your patch is applied to my source tree, can you know how to use >>>> -pflash? >> Sorry, i made a mistake. I wanted to ask you how to use -pflash if >> your patch is not applied. > > I don't think you can use pflash in a PC system when my patch is not > applied. I think without the patch qemu will create the pflash drive > internally, but it will not be hooked to a device that the emulated PC > system can see. > > I attached a log of me interacting with the pflash device under the > EFI shell on OVMF *with* the patch applied. > Great, thanks a lot. Let me try next week.
> Thanks, > > -Jordan > -- Regards, Zhi Yong Wu