[fedora-arm] f21 + qemu requires manually passing a dtb?

[Paul Whalen]

----- Original Message -----
> On 11/19/2014 10:23 AM, Peter Robinson wrote:
> >>>>> Just trying the F21 beta (and
> >>>>> Fedora-Minimal-armhfp-21-20141117-sda.raw)
> >>>>> under
> >>>>> qemu. Seems like these versions both require explicitly passing in a
> >>>>> dtb
> >>>>> to
> >>>>> qemu to actually boot. Well, maybe it's booting and I'm just not
> >>>>> getting
> >>>>> any
> >>>>> serial output, can't really tell.
> >>>>>
> >>>>> Passing a dtb to qemu wasn't required for the F20 GA release at least,
> >>>>> and
> >>>>> still isn't required with F21 qemu-system-arm, so presumably it's not a
> >>>>> qemu
> >>>>> regression.
> >>>
> >>>
> >>> Fedora 21 requires the use of a dtb to boot the multiplatform kernel.
> >>> This
> >>> changed
> >>> around the 3.16 RC's (iirc).
> >>>
> >>>>>
> >>>>> Having to pass a dtb is kind of a pain for management tools, it's
> >>>>> another
> >>>>> file
> >>>>> that needs to handled. And the docs say it shouldn't be required:
> >>>>>
> >>>>> https://fedoraproject.org/wiki/Architectures/ARM/F21/Installation#For_Versatile_Express_Emulation_with_QEMU
> >>>
> >>>
> >>> Thanks, I will adjust the page.
> >>>
> >>
> >> Medium/long term we should consider changing the docs to recommend using
> >> qemu-system-arm -M virt, since that's where all the virt improvements are
> >> generally going to take place, and it doesn't require an explicit dtb
> >> (since
> >> it generates ones behind the scene). That will also be the virt machine
> >> type
> >> used for aarch64, so it will be nice to have parity there.

What command should be used? When I add in -M virt and do not include a dtb, I
dont get any output on the serial console (a9, a15) using qemu-system-arm-2.1.2-6.fc21.x86_64.

Many thanks,
Paul


> >
> > That certainly sounds the best route. Does that allow the use of
> > virtio* for storage/network/display etc?
> >
> 
> It gives virtio for storage/network automatically, in fact it only supports
> virtio.
> 
> virtio display doesn't exist upstream yet. There's work on one but it's a
> ways
> off AIUI
> 
> Though my understanding is that soon people will be looking at adding some
> manner of PCI support to -M virt, which may open the doors for getting
> graphics to work. But I'm pretty ignorant WRT the technical details so I'm
> not
> really sure.
> 
> -M virt also has the best integration for KVM for running on arm hardware, so
> provides some parity there as well.
> 
> - Cole
>