From: Markus Armbruster <armbru@redhat.com>
To: Eduardo Habkost <ehabkost@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Peter Krempa <pkrempa@redhat.com>,
qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
libvir-list@redhat.com, qemu-devel@nongnu.org,
Max Reitz <mreitz@redhat.com>,
Stefan Hajnoczi <stefanha@redhat.com>,
Christoph Hellwig <hch@lst.de>,
"Dr . David Alan Gilbert" <dgilbert@redhat.com>
Subject: Re: [PATCH] virtio-blk: drop deprecated scsi=on|off property
Date: Fri, 30 Apr 2021 09:42:05 +0200 [thread overview]
Message-ID: <87lf905icy.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <20210429180352.ohhfz4kwyxapbiyl@habkost.net> (Eduardo Habkost's message of "Thu, 29 Apr 2021 14:03:52 -0400")
Eduardo Habkost <ehabkost@redhat.com> writes:
> On Thu, Apr 29, 2021 at 04:52:21PM +0100, Stefan Hajnoczi wrote:
>> The scsi=on|off property was deprecated in QEMU 5.0 and can be removed
>> completely at this point.
>>
>> Drop the scsi=on|off option. It was only available on Legacy virtio-blk
>> devices. Linux v5.6 already dropped support for it.
>>
>> Remove the hw_compat_2_4[] property assignment since scsi=on|off no
>> longer exists. Old guests with Legacy virtio-blk devices no longer see
>> the SCSI host features bit.
>>
>
> This means pc-2.4 will now break guest ABI if using virtio-blk
> devices, correct?
>
> This looks like a sign we should have deprecated pc-2.4 a long
> time ago.
The last batch of PC machine type retiring was pc-1.0 to pc-1.3:
deprecated in 5.0 (commit 30d2a17b4, Dec 2019), dropped in 6.0 (commit
f862ddbb1, just weeks ago). pc-1.3 was a bit over seven years old when
we released 5.0. pc-2.4 will be six years old by the time we release
6.1. Fair game?
>> Live migrating old guests from an old QEMU with the SCSI feature bit
>> enabled will fail with "Features 0x... unsupported. Allowed features:
>> 0x...". We've followed the QEMU deprecation policy so users have been
>> warned...
>>
>
> Were they really warned, though? People running
> "-machine pc-i440fx-2.4" might be completely unaware that it was
> silently enabling a deprecated feature.
We've gotten better at documenting deprecations, but we're still bad at
warning on use of deprecated features.
[...]
next prev parent reply other threads:[~2021-04-30 7:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-29 15:52 [PATCH] virtio-blk: drop deprecated scsi=on|off property Stefan Hajnoczi
2021-04-29 16:16 ` Peter Krempa
2021-05-04 14:31 ` Stefan Hajnoczi
2021-04-29 18:03 ` Eduardo Habkost
2021-04-30 7:42 ` Markus Armbruster [this message]
2021-04-30 7:58 ` Peter Krempa
2021-05-04 10:45 ` Dr. David Alan Gilbert
2021-05-04 14:28 ` Stefan Hajnoczi
2021-05-04 14:32 ` Stefan Hajnoczi
2021-05-04 15:26 ` Eduardo Habkost
2021-04-30 5:47 ` Michal Prívozník
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