Re: [Qemu-devel] [PATCH 6/6] pc_sysfw: change rom_only default to 0

[Paolo Bonzini]

Il 30/04/2013 05:51, Jordan Justen ha scritto:
> The rom in qemu is read-only. In kvm, it has been read-write. That is
> different behavior.

And it was a problem, hence it was reverted.

> I assume with kvm readonly support, at some point the rom may be
> read-only or read/write under kvm depending on the capabilities.

No, this would be bad.

> Anyway, would this work:
> if (-pflash is not used) {
>   qemu and kvm always use a 'rom' mode
> } else if (non-kvm or kvm read-only capable) {
>   PC flash used
> } else {
>   die "kvm+pflash requires read-only capability"
> }
> 
> Someone could create a flash capable VM on qemu or newer kvm, and then
> have trouble with it on an older kvm, but the chance of potential
> issues seems greatly reduced.
> 
> For people using rom firmware, this should have no impact.

Yes, _this_ would work because it requires a special command line, and
it would have never worked before.

Paolo