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Date:      Thu, 04 Apr 2019 03:02:21 +0000
From:      bugzilla-noreply@freebsd.org
To:        bugs@FreeBSD.org
Subject:   [Bug 236922] Virtio fails as QEMU-KVM guest with Q35 chipset on Ubuntu 18.04.2 LTS
Message-ID:  <bug-236922-227-2jlRvKh4Hb@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-236922-227@https.bugs.freebsd.org/bugzilla/>
References:  <bug-236922-227@https.bugs.freebsd.org/bugzilla/>

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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D236922

--- Comment #9 from Tommy P <tommyhp2@gmail.com> ---
(In reply to Bryan Venteicher from comment #8)

Hi Bryan,

Thank you for the feedback.  I've been digging further to learn more about =
the
FreeBSD's internal while improving my C/C++ skills.  I've found that there =
are
2 sets of device IDs:  PCI (which FreeBSD currently support) and the PCIe
(which I think your work would support).  I'll give them a try a report bac=
k if
I've found any issue.

While doing a lot of trial and error, I've found something puzzling.  If I
build my custom kernel w/o debug, traces, and netmap (in addition to
unnecessary drivers), pciconf shows correctly for the PCIe root:

pcib1@pci0:0:2:0:       class=3D0x060400 card=3D0x00001b36 chip=3D0x000c1b3=
6 rev=3D0x00
hdr=3D0x01
    vendor     =3D 'Red Hat, Inc.'
    device     =3D 'QEMU PCIe Root port'
    class      =3D bridge
    subclass   =3D PCI-PCI
    cap 10[54] =3D PCI-Express 2 root port max data 128(128) ARI disabled
                 link x1(x1) speed 2.5(2.5) ASPM disabled(L0s)
                 slot 0 power limit 0 mW HotPlug(present) surprise Attn But=
ton
PC(on) EI(disengaged)
    cap 11[48] =3D MSI-X supports 1 message
                 Table in map 0x10[0x0], PBA in map 0x10[0x800]
    cap 0d[40] =3D PCI Bridge card=3D0x00001b36
    ecap 0001[100] =3D AER 2 0 fatal 0 non-fatal 0 corrected

However, when added back in the debug, traces, and netmap (still w/o the ex=
tra
drivers) similar to the GENERIC kernel, that same controller becomes:

none0@pci0:0:2:0:       class=3D0x060400 card=3D0x00001b36 chip=3D0x000c1b3=
6 rev=3D0x00
hdr=3D0x01
    vendor     =3D 'Red Hat, Inc.'
    device     =3D 'QEMU PCIe Root port'
    class      =3D bridge
    subclass   =3D PCI-PCI
    bar   [10] =3D type Memory, range 32, base 0xfd212000, size 4096, enabl=
ed
    bus range  =3D 1-1
    window[1c] =3D type I/O Port, range 16, addr 0xe000-0xdfff, disabled
    window[20] =3D type Memory, range 32, addr 0xfd000000-0xfd1fffff, enabl=
ed
    window[24] =3D type Prefetchable Memory, range 64, addr
0xfea00000-0xfebfffff, enabled
    cap 10[54] =3D PCI-Express 2 root port max data 128(128) ARI disabled
                 link x1(x1) speed 2.5(2.5) ASPM disabled(L0s)
                 slot 0 power limit 0 mW HotPlug(present) surprise Attn But=
ton
PC(on) EI(disengaged)
    cap 11[48] =3D MSI-X supports 1 message
                 Table in map 0x10[0x0], PBA in map 0x10[0x800]
    cap 0d[40] =3D PCI Bridge card=3D0x00001b36
    ecap 0001[100] =3D AER 2 0 fatal 0 non-fatal 0 corrected

as seen from pciconf.  Note how it's 'pcib1' w/o debug+traces and 'none0' w=
ith
debug+traces.  I don't know if the bug is with the VirtIO driver or the
debug/trace.  Perhaps its by design?  This from src r345840.

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