Re: [Bug 1924912] VirtIO drivers don't work on Windows: "GLib: Too many handles to wait for!" crash

[Stefan Weil <sw@weilnetz.de>]

Am 19.04.21 um 16:30 schrieb Laurent Vivier:

> Le 19/04/2021 à 12:39, Stefan Weil a écrit :
>> I can confirm the issue also with latest official QEMU sources.
>>
>> Related issue URLs:
>>
>> https://github.com/tesseract-ocr/tesseract/issues/2838
>>
>> https://bugs.launchpad.net/qemu/+bug/1924912
>>
>> Instructions and files required to reproduce the issue:
>>
>> https://qemu.weilnetz.de/test/bugs/1924912/
>>
>> Michael, Laurent, maybe you have an idea how to narrow down this issue?
> Could it be related to the number of file descriptors that can differ
> between linux an windows?
>
> We have a series of patches that sets the number of queues to the number
> of vCPU:
>
> a4eef0711b2c vhost-user-blk-pci: default num_queues to -smp N
> 9445e1e15e66 virtio-blk-pci: default num_queues to -smp N
> 6a558822849f virtio-scsi-pci: default num_queues to -smp N
> 4e5163bd8444 virtio-scsi: introduce a constant for fixed virtqueues
> 1436f32a84c3 virtio-pci: add virtio_pci_optimal_num_queues() helper
>
> And I think it can have inpact on the number of open file descriptors.
>
> You can try by specifiying "num_queues=1" with the virtio interfaces on the QEMU command line.
> (ot choose a machine type earlier than 5.2)
>
> Thanks,
> Laurent

I tried different machine types. That did not help.

The full command line which did not work was this one:

qemu-system-i386 -s -m 512M -cpu max -d guest_errors -smp 2 -device 
VGA,vgamem_mb=64 -drive file=_disk_image,format=raw,index=0,media=disk 
-device ich9-ahci -usb -device virtio-serial -chardev 
stdio,id=stdout,mux=on -device virtconsole,chardev=stdout -device 
isa-debugcon,chardev=stdout -device virtio-rng-pci -soundhw pcspk 
-device sb16 -netdev 
user,id=breh,hostfwd=tcp:127.0.0.1:8888-10.0.2.15:8888,hostfwd=tcp:127.0.0.1:8823-10.0.2.15:23,hostfwd=tcp:127.0.0.1:8000-10.0.2.15:8000,hostfwd=tcp:127.0.0.1:2222-10.0.2.15:22 
-device e1000,netdev=breh -kernel Kernel/Kernel -append hello

QEMU works nicely when I remove "-device virtio-serial" and "-device 
virtconsole,chardev=stdout" from that command line. How would I have to 

modify those arguments to limit the number of queues?

Thanks,

Stefan