Re: [Qemu-devel] [PATCH 0/3] Remove legacy sysfw code

[Paolo Bonzini <pbonzini@redhat.com>]

Il 03/06/2013 23:56, Jordan Justen ha scritto:
> You seem to have a much better handle than I do on machine migration
> and backward compatibility issues within QEMU.
> 
> One difference we'll see from this series is that...
> 
> With QEMU 1.2, an error would always be generated with:
> qemu-system-x86_64 -M pc-1.2 -enable-kvm -pflash flash.bin
> 
> Whereas in QEMU 1.6 the same command may succeed if the kernel
> supports the READONLY kvm feature.
> 
> Will one other result of this series be that basically any of the
> older pc machines can now use -pflash?

Yes, that's it and it's fine (it's a new feature, it doesn't matter).
Similarly,

   qemu-system-x86_64 -M pc-1.0 -pflash flash.bin

will create flash while it would have failed in real QEMU 1.0.

The main difference is that with QEMU 1.2 this will use read-only flash:

   qemu-system-x86_64 -M pc-1.2

whereas in QEMU 1.6 the same command will always use BIOS, as has always
been the case with

   qemu-system-x86_64 -M pc-1.2 --enable-kvm

These semantics are much simpler to use and explain, and probably should
have been like that all the time.

Paolo

> Anyway, that doesn't seem like a big issue to me, so for the series:
> Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>
> 
> -Jordan
> 
> On Mon, Jun 3, 2013 at 8:19 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> The sysfw code to choose between ROM and flash BIOS was a bad idea,
>> because it triggered different behavior between TCG and KVM.  We
>> deleted the behavior in 1.5, but we left the code around because
>> it was close to the release.  Now it's time to delete it.
>>
>> Paolo Bonzini (3):
>>   remove read-only pc_sysfw_flash_vs_rom_bug_compatible
>>   pc_sysfw: remove the rom_only property
>>   pc_sysfw: do not make it a device anymore
>>
>>  default-configs/i386-softmmu.mak   |   1 -
>>  default-configs/x86_64-softmmu.mak |   1 -
>>  hw/block/Makefile.objs             |   1 -
>>  hw/i386/Makefile.objs              |   1 +
>>  hw/i386/pc.c                       |   5 +-
>>  hw/i386/pc_piix.c                  |  16 +----
>>  hw/i386/pc_q35.c                   |   2 +-
>>  hw/{block => i386}/pc_sysfw.c      | 135 +++----------------------------------
>>  include/hw/i386/pc.h               |   6 +-
>>  9 files changed, 18 insertions(+), 150 deletions(-)
>>  rename hw/{block => i386}/pc_sysfw.c (62%)
>>
>> --
>> 1.8.1.4
>>
>>
> 
>