[Qemu-devel] Re: RFC: emulation of system flash

[Jordan Justen]

On Thu, Mar 10, 2011 at 11:12, Gleb Natapov <address@hidden> wrote:
> On Thu, Mar 10, 2011 at 10:59:07AM -0800, Jordan Justen wrote:
>> Yes, this definitely could add firmware upgrade issues, but I thought
>> this could be the responsibility of the firmware itself.  For example,
>> OVMF could have an outside of VM tool to merge new releases, or it
>> could have an inside of VM firmware update process.
> Why require another tool if can do without? I don't see any advantages
> in storing firmware code and its non-volatile storage in the same image,
> but I do see disadvantages.

I agree.  The implications of a firmware image getting out of sync
with qemu were a bit of a concern to me.  But, having both -bios +
-flash just below -bios was starting to seem a bit complicated.

And, I guess as a firmware developer, I thought it might be
interesting to consider enabling a firmware update process within the
VM. :)

How about?
1) Pure rom:
-bios bios.bin
2) Rom + flash below rom:
-bios bios.bin,flash=flash.bin
3) Pure flash:
-bios flash=flash.bin

Or, with a separate new -flash option:
1) Pure rom:
-bios bios.bin
or no -bios or -flash parameters
2) Rom + flash below rom:
-bios bios.bin -flash flash.bin
3) Pure flash:
-flash flash.bin

> It is not even about performance (which will be very bad for 1MB). KVM
> can't run code from MMIO region, so the part that contains firmware
> has to be memory.

Hmm.  That's good to know. :)

So, perhaps this feature should build upon the other feature you and
Jan are discussing.  When will it become available?

Thanks,

-Jordan