The upstream QEMU community is raising the possibility of deprecating,
and subsequently deleting, support for running emulation guests on
32-bit *hosts*. Running 32-bit guests would *not* be affected.
See this thread:
https://lists.gnu.org/archive/html/qemu-devel/2019-09/msg06168.html
IOW, if you have a armv7/i686/ppc *host* machine, you would no longer be
able to use QEMU for either full machine system emulation (TCG), nor linux
userspace emulators (TCG). Potentially KVM for 32-bit *host* would be
dropped too, but QEMU might deal with that separately, to align with
kernel support for KVM on 32-bit.
In simple terms, we're talking this proposed matrix for running virtual
machines or linux userspace with emulated CPU architectures:
| Host 32-bit | Host 64-bit
-------------+-------------+------------
Guest 32-bit | dropped | supported
Guest 64-bit | dropped | supported
Given that i686 is no longer composed in Fedora, that leaves armv7 as the
Fedora host arch which would be affected.
If upstream goes ahead, we have 2 releases with deprecation[1], so the earliest
it would be deleted is the QEMU release in Aug 2020, which would be Fedora 33
timeframe IIUC. At that time any RPM with a dependancy on QEMU on 32-bit would
need some %ifarch, or ExclusiveArch magic.
I'm assuming there's nothing in Fedora infra that uses 32-bit hosts, as
IIUC, our armv7 koji builders are all on aarch64 hosts.
Does anyone know of, or have, any critical/important use cases that would
be disrupted by QEMU dropping 32-bit *host* support ? If so, let me know
here & I can forward feedback on. Or feel free to go direct to QEMU thread
upstream.
Regards,
Daniel
[1]
https://qemu.weilnetz.de/doc/qemu-doc.html#Deprecated-features
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