Re: [edk2-devel] [PATCH 1/2] OvmfPkg/build.sh: use newer '-drive if=pflash' syntax when running qemu

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 7/24/19 7:26 PM, Jordan Justen wrote:
> On 2019-07-24 05:27:28, Philippe Mathieu-Daudé wrote:
>> On 7/24/19 4:54 AM, Jordan Justen wrote:
>>> On 2019-07-23 18:51:00,  wrote:
>>>> Specify the firmware to use via the newer '-drive if=pflash' syntax
>>>> which allows specifying the raw format and readonly parameters. This
>>>> avoids warnings with newer version of QEMU.
>>>>
>>>> Signed-off-by: Rebecca Cran <rebecca@bsdio.com>
>>>> ---
>>>>  OvmfPkg/build.sh | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/OvmfPkg/build.sh b/OvmfPkg/build.sh
>>>> index a2c4eff2a5..e2890ff762 100755
>>>> --- a/OvmfPkg/build.sh
>>>> +++ b/OvmfPkg/build.sh
>>>> @@ -268,7 +268,7 @@ if [[ "$RUN_QEMU" == "yes" ]]; then
>>>>    fi
>>>>    ln -sf $FV_DIR/OVMF.fd $QEMU_FIRMWARE_DIR/bios.bin
>>>>    if [[ "$ENABLE_FLASH" == "yes" ]]; then
>>>> -    QEMU_COMMAND="$QEMU_COMMAND -pflash $QEMU_FIRMWARE_DIR/bios.bin"
>>>> +    QEMU_COMMAND="$QEMU_COMMAND -drive if=pflash,format=raw,readonly,file=$QEMU_FIRMWARE_DIR/bios.bin"
>>>
>>> It looks like we set ENABLE_FLASH for qemu 1.6 and newer. Does this
>>> work on 1.6?
>>>
>>> Also, I don't think we want readonly. Read-write should allow
>>> non-volatile variables to persist across multiple boot.
>>
>> This flash only contains the CODE, not the non-volatile VARS, using
>> readonly makes sense to me.
> 
> That's not the case here. The build.sh support uses a combined
> code/vars binary. Originally the qemu pflash support only supported a
> single binary. At this point we can probably assume that a new enough
> version of qemu is available that supports multiple pflash devices, so
> build.sh could be upgraded to use the split binaries.

Oh I did not know, this show how young I'm ;)

> Hmm, it looks like qemu 2.0 is when the multiple flash device support
> was added: https://wiki.qemu.org/ChangeLog/2.0
> 
> The build.sh script currently attempts to detect 1.6 and newer for
> flash support. pflash first appeared in 1.1, but kvm support was added
> in 1.6. I think it'd be reasonable to alter the script to not use
> flash for qemu < 2.0, to enable using separate code and vars binaries.

Where can I find the range of QEMU versions used by EDK2?
I'm trying to understand why it is important to still maintain scripts
for a such old version.

Thanks,

Phil.