Re: some QEMU success in running armv7

Nice review. infortunately kvm does not work ? and a qemu vm without kvm is
very slow and useless.

Il ven 19 mag 2023, 04:49 Thomas David Rivers <rivers@dignus.com> ha
scritto:

>
> Just f.y.i. - here's the steps I was able to deduce today
> to get FreeBSD armv7 running under qemu... just in case
> someone goes looking for this... (I was doing this on a
> FreeBSD 12.3-RELEASE x86_64 system.)
>
>
> 1.   Retrieve the armv7 image from:
>         fetch
> https://download.freebsd.org/releases/arm/armv7/ISO-IMAGES/13.2/FreeBSD-13.2-RELEASE-arm-armv7-GENERICSD.img.xz
>      and unzip it.   This is an actual hard-drive image of a working
>      system.
>
> 2.  Assuming the qemu port has been installed - this command
>     starts that system
>
>     qemu-system-arm -M virt -m 512m -nographic \
>        -bios edk2-arm-code.fd \
>        -hda FreeBSD-13.2-RELEASE-arm-armv7-GENERICSD.img
>
>     the existing terminal will be the console.  There is no
>     networking.
>
>     There root user's password is 'root'.
>
> Unfortunately this doesn't provide networking in the guest.  This
> compilation of QEMU also doesn't support the "-netdev user" mode
> of networking so I can't take advantage of that.  (The FreeBSD 12.3
> host is using QEMU emulator version 7.2.0 - from just the pkg
> install.)  However, I found that using this option on qemu:
>
>     -nic tap,ifname=tap7,script=no,downscript=no
>
> got it to use the tap interface on the host to emulate the virtio
> device to the guest.
>
> I also found this discussion regarding alignment issues in the
> virtio driver in armv7:
>
>
> https://forums.freebsd.org/threads/kernel-panic-on-armv7-with-qemu.89016/#post-610281
>
> that resulted in PR 271288.   Apparently it's because of newer versions
> of QEMU doing a better job at reporting unaligned memory accesses in the
> guest for the armv7 "ldm" instruction.
>
> When I use the tap interface, I did get the exact panic mentioned
> in the forum and the PR.
>
> I did find that specifying the rtl8139 device worked around the panic
> with the QEMU option:
>
>   -nic tap,ifname=tap7,script=no,downscript=no,model=rtl8139
>
> by the way - tap7 happens to be a tap device I'd already configured
> on the host FreeBSD 12.3 system - if you're doing this yourself,
> it will likely need to be a different tap device, see this
> write-up for info about how to configure a tap + bridge on your
> FreeBSD host:
>
> http://bsdwiki.reedmedia.net/wiki/networking_qemu_virtual_bsd_systems.html
>
> So - it seems a newer version of the armv7 kernel with the patch
> applied will fix the virtio driver problem, until then, model=rtl8139
> works around it and I have networking and everything!
>
>         - Dave R. -
>
> --
> rivers@dignus.com                        Work: (919) 676-0847
> Get your mainframe programming tools at http://www.dignus.com
>
>