On 12/8/21 11:36 pm, Gerd Hoffmann wrote:
> Hi,
>
>> While that all worked fine, probably with better performance (as Gerd
>> mentioned) it was still unsatisfying that I couldn't make the plain ide
>> work. It turns out that the ide interface can work without changes to
>> the initrd but invocation requires separate -drive and -device options,
>> somewhat like James' scsi version, namely:
>>
>> -device ahci,id=ahci \
>> -device ide-hd,drive=ide0,bus=ahci.0 \
>> -drive
>> if=none,id=ide0,file=disk.img,format=raw,cache=none,index=0,media=disk \
>
> That is again something different, namely sata ...
>
>> instead of my original shortcut version:
>>
>> -drive file=disk.img,format=raw,cache=none,index=0,media=disk \
>
> ... while this is the older pata (with "-machine pc").
>
> To add even more confusion: When using the more modern q35 chipset
> ("-machine q35") qemu will also use the more modern sata when you
> use the shortcut version to attach your disk.
>
> So, in general it is a good idea to explicitly add the storage
> controller and devices you want as suggested by James. Results
> in less surprises ;)
>
Thanks Gerd,
That is the missing piece of the puzzle. I added "-machine q35" and
reverted to the shortcut -drive option and boot was successful with
UEFI. Although I will use the longer form in future, it was still
annoying that the shortcut version failed. The pata/sata explanation is
quite satisfying and I can finally let this issue go :)
chris
>> I'll probably stick with the better performing scsi version from now on
>> although it's still interesting that the shortcut version works without
>> UEFI but fails with UEFI.
>
> I've seen guest driver failures due to missing firmware initialization
> before. Specifically firmware not setting the busmaster bit in pci
> config space leading to guest driver's dma transfers failing (which of
> course is a guest driver bug).
>
> I can imagine ovmf taking shortcuts for direct kernel boot could have
> that kind of effect too, and of course it could vary depending on the
> kind of storage controller used.
>
> take care,
> Gerd
>
>
>
>
>
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