Re: intermittent hang in qos-test for qemu-system-i386 on 32-bit arm host

[Coiby Xu <coiby.xu@gmail.com>]

On Sun, Jul 11, 2021 at 06:23:41AM -0700, Richard Henderson wrote:
>On 7/11/21 5:16 AM, Peter Maydell wrote:
>>On Sun, 11 Jul 2021 at 13:10, Coiby Xu <coiby.xu@gmail.com> wrote:
>>>
>>>Hi Peter,
>>>
>>>On Sat, Jul 10, 2021 at 02:30:36PM +0100, Peter Maydell wrote:
>>>>I've noticed recently that intermittently 'make check' will hang on
>>>>my aarch32 test system (really an aarch64 box with an aarch32 chroot).
>>>
>>>I have a newbie question. How do you do an aarch32 chroot on an aarch64
>>>box? At least, this issue seems to be not reproducible on an aarch64 box
>>>directly. I specifically ran the qos-test for 5 consecutive times and
>>>each time the test could finish successfully,
>>
>>Your aarch64 host CPU needs to support aarch32 at EL0 (some
>>AArch64 CPUs are pure-64 bit these days). The host kernel needs
>>to implement the 32-bit compat layer. It probably also needs to be
>>built for 4K pages (which mostly means "not RedHat"). Then you can
>>set up the 32-bit chroot however you'd normally set up a chroot
>>(for Debian you can do this with debootstrap; other distros will vary;
>>schroot is also a bit nicer than raw chroot IMHO.)
>
>If you do have a kernel built with 64k pages ("RedHat"), but you do 
>have a host cpu that supports aarch32 at EL1 and EL0, then you can run 
>aarch32 under KVM.
>
>The command-line I use is
>
>../run/bin/qemu-system-aarch64 -m 4096 -smp 8 -nographic \
>  -M virt -cpu host,aarch64=off --accel kvm \
>  -kernel vmlinuz-4.19.0-16-armmp-lpae \
>  -initrd initrd.img-4.19.0-16-armmp-lpae \
>  -append 'console=ttyAMA0 root=/dev/vda2' \
>  -drive if=none,file=hda.q,format=qcow2,id=hd,discard=on \
>  -device virtio-blk-device,drive=hd \
>  -netdev tap,id=tap0,br=virbr0,helper=/usr/libexec/qemu-bridge-helper \
>  -device virtio-net-device,netdev=tap0
>
>I believe that I had to perform the install under tcg because I 
>couldn't find the right magic to boot off the debian cdrom with kvm.

Thanks for the instructions! Since this issue is also reproducible on 
qemu-system-i386 guest x86-64 Linux host according to Peter's new email, 
I'll check it on i386 guest first.

>
>
>r~

-- 
Best regards,
Coiby