[libvirt] [Qemu-devel] [PULL v3 00/54] Kconfig conversion, excluding ARM and MIPS

[Laszlo Ersek]

On 03/21/19 01:53, Laszlo Ersek wrote:
> Hi Paolo,
> 
> (+libvir-list)
> 
> I'd like to report a regression introduced by this patch set:
> 
> On 03/07/19 21:58, Paolo Bonzini wrote:
>> The following changes since commit
>> 6cb4f6db4f4367faa33da85b15f75bbbd2bed2a6:
>>
>>   Merge remote-tracking branch
>>   'remotes/cleber/tags/python-next-pull-request' into staging
>>   (2019-03-07 16:16:02 +0000)
>>
>> are available in the Git repository at:
>>
>>   git://github.com/bonzini/qemu.git tags/for-upstream-kconfig
>>
>> for you to fetch changes up to
>> 576c3f2f16e7392e28cc9fe10d9a920d67d3645b:
>>
>>   kconfig: add documentation (2019-03-07 21:54:22 +0100)
>>
>> ----------------------------------------------------------------
>> Initial Kconfig work, excluding ARM and MIPS
>>
>> ----------------------------------------------------------------
> 

In brief, the regression is that the aarch64 system emulator now lists
the "virtio-vga" device for the "virt" machine type:

$ qemu-system-aarch64 -M virt -device \? | grep virtio-vga
name "virtio-vga", bus PCI

Here's where I think the issue was introduced:

(1) In commit 82f5181777eb ("kconfig: introduce kconfig files",
2019-03-07), VIRTIO_VGA was introduced simply as a bool (with no other
clauses) in "hw/display/Kconfig".

(2) In commit 7c28b925b7e1 ("build: convert pci.mak to Kconfig",
2019-03-07), VIRTIO_VGA received the following clauses:

    default y if PCI_DEVICES
    depends on VIRTIO_PCI
    select VGA

This is too lax, because it permits virtio-vga for aarch64, while that
shouldn't happen (and it doesn't matches the previous state of the tree).

(3) In commit b42075bb7767 ("virtio: express virtio dependencies with
Kconfig", 2019-03-07), the determination of virtio-vga was switched to
the Kconfig system. Importantly, in this patch, the line

  CONFIG_VIRTIO_VGA=y

was removed *only* from the following file:

  default-configs/i386-softmmu.mak

(4) Both of the remaining instances of

  CONFIG_VIRTIO_VGA=y

were then removed in commit 9483cf27dd36 ("hppa-softmmu.mak: express
dependencies with Kconfig", 2019-03-07) and commit 87f9108bad0c ("ppc64:
Express dependencies of 'pseries' and 'powernv' machines with kconfig",
2019-03-07), from files

  default-configs/hppa-softmmu.mak
  default-configs/ppc64-softmmu.mak

respectively.


Therefore I think commit 7c28b925b7e1 has the bug. The VIRTIO_VGA
restriction

  depends on VIRTIO_PCI

should now be replaced with

  depends on VIRTIO_PCI && (PC || DINO || PSERIES)

Thanks
Laszlo