FreeBSD Big Endian in a VM and VirtIO

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Hi!

How do you run FreeBSD with Big Endian in a VM?

Is qemu the de facto only hypervisor used for this?

To avoid CPU emulation, I installed Debian (Little Endian) on a Raptor =
Blackbird to run a FreeBSD (Big Endian) VM with qemu.

Currently, I=E2=80=99m investigating this bug:

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D294706

I think the cause is byte swaps in =
sys/dev/virtio/pci/virtio_pci_modern.c (by virtio_htog*() or =
virtio_gtoh*() function calls) that shouldn=E2=80=99t be done. At least =
if I remove these in my setup, the bug disappears. Now, I wonder, are =
these byte swaps incorrect in my setup but necessary in others (due to =
another hypervisor or the endianness of the host system)?

In my understanding, at the lines where virtio_pci_modern.c uses the =
virtio_htog*() functions, it reads a value from the PCI bus. Since the =
PCI bus uses little endian, it requires a byte swap in a big endian VM, =
but this is already done internally by the bus_space API. So, this would =
mean the byte swaps in virtio_pci_modern.c are incorrect in general and =
shouldn=E2=80=99t be done.

Timo=

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