Bug#1143094: hw-detect: Fails to detect network card under BIOS boot in qemu

Cyril Brulebois <[email protected]> Thu, 30 Jul 2026 13:15:24 +0200
Newsgroups gmane.linux.debian.devel.boot
Organization Debian
Message-ID <20260730111524.en7oyqjm6bwu2s4d__9879.46144757501$1785411693$gmane$org@mraw.org>
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Hi Roland,

Thanks for the report.

Roland Clobus <[email protected]> (2026-07-30):
> Hello maintainers of hw-detect,
>=20
> The new version of ethdetect.sh does not detect the network interfaces wh=
en booting from BIOS.
>=20
> This can be seen on openQA [1] where the installer fails to find the netw=
ork interfaces for the BIOS scenarios. The UEFI scenarios still work.
>=20
> From the d-i syslog (broken, BIOS) [2]:
> Jul 29 21:33:12 main-menu[430]: INFO: Menu item 'ethdetect' selected
> Jul 29 21:33:17 net/hw-detect.hotplug: Detected hotpluggable network inte=
rface lo
> Jul 29 21:33:18 net/hw-detect.hotplug: Detected hotpluggable network inte=
rface ens4
> Jul 29 21:33:18 kernel: [   30.969705] virtio_net virtio0 ens4: renamed f=
rom eth0
> Jul 29 21:33:19 check-missing-firmware: looking at dmesg for the first ti=
me
> Jul 29 21:33:19 check-missing-firmware: saving timestamp for a later use:=
 [   30.969705]
> Jul 29 21:33:19 check-missing-firmware: no missing firmware in loaded ker=
nel modules
>=20
> From the d-i syslog (last working, BIOS) [3]:
> Jul 29 16:03:07 main-menu[430]: INFO: Menu item 'ethdetect' selected
> Jul 29 16:03:13 net/hw-detect.hotplug: Detected hotpluggable network inte=
rface lo
> Jul 29 16:03:13 kernel: [   31.465192] virtio_net virtio0 ens4: renamed f=
rom eth0
> Jul 29 16:03:13 net/hw-detect.hotplug: Detected hotpluggable network inte=
rface ens4
> Jul 29 16:03:14 check-missing-firmware: looking at dmesg for the first ti=
me
> Jul 29 16:03:14 check-missing-firmware: saving timestamp for a later use:=
 [   31.465192]
> Jul 29 16:03:14 check-missing-firmware: no missing firmware in loaded ker=
nel modules
> Jul 29 16:03:14 check-missing-firmware: taking network interface ens4 up/=
down
> Jul 29 16:03:15 check-missing-firmware: looking at dmesg again, restartin=
g from timestamp: [   31.465192]
> Jul 29 16:03:15 check-missing-firmware: timestamp found, truncating dmesg=
 accordingly
> Jul 29 16:03:15 check-missing-firmware: keeping timestamp (no new lines):=
 [   31.465192]
> Jul 29 16:03:15 check-missing-firmware: no missing firmware in loaded ker=
nel modules
>=20
> After 1.176 entered unstable, all BIOS installer tests started to fail. T=
here are no version differences in the other udebs, so that's why I report =
against hw-detect.
>=20
> I think it might be caused by the 'Change hw-detect/firmware-lookup
> type to string' change, since that influences whether the network
> interface is taken down and up again.

Commit 619ba547da555a9a87290c8ce9315c3db5376cf0 looks much more plausible
to me, as interface names can be preceeded by a number of spaces, with a
first column that's right-aligned. Depending on if and how the heading is
word-wrapped (I'm seeing Inter-\nface in several cases but I'm not
checking the actual implementation), the number of interfaces, and their
name length, a number of them can go missing. With default QEMU settings
on bookworm, latest mini.iso gets:

    Inter-|
     face |
        lo:
      ens3:

which probably explains the issue down the line.


Cheers,
--=20
Cyril Brulebois ([email protected])            <https://debamax.com/>
D-I release manager -- Release team member -- Freelance Consultant

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