[xpost,repost] VGA false positive in dmesg?

[Ottavio Caruso]

On 04/08/2020 11:00, Eugene Grosbein wrote:
> 04.08.2020 15:08, Ottavio Caruso via freebsd-hackers wrote:
>> Hi,
>>
>> [originally mailed to freebsd-questions, but I didn't get any feedback over there]
>>
>> I've launched a FreeBSD 12.1 instance in qemu (pay attention to "-vga
>> none"). Host is Linux:
>>
>> qemu-system-x86_64 \
>> -drive if=virtio,file=/home/oc/VM/img/freebsd.image,index=0,media=disk \
>> -M q35,accel=kvm -m 250M -cpu host -smp $(nproc) \
>> -nic user,hostfwd=tcp:127.0.0.1:5554-:22,model=virtio-net-pci \
>> -daemonize -display none -vga none \
>> -serial mon:telnet:127.0.0.1:6664,server,nowait \
>>
>> In the guest:
>>
>> oc at FreeBSD:~ % pciconf -vl
>> hostb0 at pci0:0:0:0:      class=0x060000 card=0x11001af4 chip=0x29c08086
>> rev=0x00 hdr=0x00
>>      vendor     = 'Intel Corporation'
>>      device     = '82G33/G31/P35/P31 Express DRAM Controller'
>>      class      = bridge
>>      subclass   = HOST-PCI
>> virtio_pci0 at pci0:0:1:0: class=0x020000 card=0x00011af4 chip=0x10001af4
>> rev=0x00 hdr=0x00
>>      vendor     = 'Red Hat, Inc.'
>>      device     = 'Virtio network device'
>>      class      = network
>>      subclass   = ethernet
>> virtio_pci1 at pci0:0:2:0: class=0x010000 card=0x00021af4 chip=0x10011af4
>> rev=0x00 hdr=0x00
>>      vendor     = 'Red Hat, Inc.'
>>      device     = 'Virtio block device'
>>      class      = mass storage
>>      subclass   = SCSI
>> virtio_pci2 at pci0:0:3:0: class=0x010000 card=0x00021af4 chip=0x10011af4
>> rev=0x00 hdr=0x00
>>      vendor     = 'Red Hat, Inc.'
>>      device     = 'Virtio block device'
>>      class      = mass storage
>>      subclass   = SCSI
>> isab0 at pci0:0:31:0:      class=0x060100 card=0x11001af4 chip=0x29188086
>> rev=0x02 hdr=0x00
>>      vendor     = 'Intel Corporation'
>>      device     = '82801IB (ICH9) LPC Interface Controller'
>>      class      = bridge
>>      subclass   = PCI-ISA
>> ahci0 at pci0:0:31:2:      class=0x010601 card=0x11001af4 chip=0x29228086
>> rev=0x02 hdr=0x00
>>      vendor     = 'Intel Corporation'
>>      device     = '82801IR/IO/IH (ICH9R/DO/DH) 6 port SATA Controller
>> [AHCI mode]'
>>      class      = mass storage
>>      subclass   = SATA
>> none0 at pci0:0:31:3:      class=0x0c0500 card=0x11001af4 chip=0x29308086
>> rev=0x02 hdr=0x00
>>      vendor     = 'Intel Corporation'
>>      device     = '82801I (ICH9 Family) SMBus Controller'
>>      class      = serial bus
>>      subclass   = SMBus
>>
>> However, in dmesg:
>>
>> oc at FreeBSD:~ % dmesg | grep -i vga
>> VT(vga): text 80x25
>> vtvga0: <VT VGA driver> on motherboard
>> vga0: <Generic ISA VGA> at port 0x3b0-0x3bb iomem 0xb0000-0xb7fff
>> pnpid PNP0900 on isa0
>>
>> I don't know how to interpret this output.
> 
> pciconf deals with PCI/PCI-E only but your guest detects ISA VGA device.
> Compare with real VGA hardware:
> 
> VT(vga): resolution 640x480
> vtvga0: <VT VGA driver> on motherboard
> vgapci0: <VGA-compatible display> port 0xb000-0xb0ff mem 0xd0000000-0xdfffffff,0xfc3f0000-0xfc3fffff,0xfc200000-0xfc2fffff irq 18 at device 5.0 on pci1
> vgapci0: Boot video device
> 
> 
>> I don't think it's a qemu issue, because I've done the same with NetBSD and OpenBSD guests and
>> there's no trace of vga in their dmesg.
> 
> Maybe your guest has hw.vga.acpi_ignore_no_vga=1 in the kernel environment
> or some other non-default "hw.vga" knobs, check it out with kenv(1)

No,I haven't got either of them set up.

.
> 
> You can also try adding to /boot/loader.conf:
> 
> hint.vtvga.0.disabled=1

This doesn't seem to work:

oc at FreeBSD:~ % cat /boot/loader.conf
hint.vtvga.0.disabled=1
oc at FreeBSD:~ % dmesg | grep -i vga 
        VT(vga): text 80x25
vtvga0: <VT VGA driver> on motherboard
vga0: <Generic ISA VGA> at port 0x3b0-0x3bb iomem 0xb0000-0xb7fff pnpid 
PNP0900 on isa0
VT(vga): text 80x25
vga0: <Generic ISA VGA> at port 0x3b0-0x3bb iomem 0xb0000-0xb7fff pnpid 
PNP0900 on isa0


-- 
Ottavio Caruso