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

[Paul Whalen]

----- Original Message -----
> 
> 
> ----- Original Message -----
> > On 11/19/2014 03:47 PM, Paul Whalen wrote:
> > >
> > >
> > > ----- 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.
> > >
> > 
> > I did this with virt-install:
> > 
> > sudo virt-install --name f21-arm-machvirt --ram 1024 --arch armv7l --disk
> > Fedora-Minimal-armhfp-21-20141117-sda.raw --import --boot
> > kernel=vmlinuz-3.17.2-300.fc21.armv7hl,initrd=initramfs-3.17.2-300.fc21.armv7hl.img,kernel_args="console=ttyAMA0
> > rw root=/dev/vda3 rootwait"
> > 
> > But looking at the libvirt generated qemu command line is probably more
> > confusing than enlightening. What command line did you use? Maybe I can
> > spot
> > the problem
> 
> From our wiki (only added -M virt):
> 
> sudo qemu-system-arm -M virt -cpu cortex-a15 -m 1024 -nographic -net nic -net
> user \
>  -append "console=ttyAMA0,115200n8 rw root=/dev/mmcblk0p3 rootwait
>  physmap.enabled=0" \
>  -kernel $KERN \
>  -initrd $INTRD \
>  -sd Fedora-$TYPE-armhfp-21_Beta-4-sda.raw
> 
> Gives serial output, but the machine type is listed as: Machine model:
> linux,dummy-virt ,
> system doesnt find the rootfs.

Driver error, the rootfs was on '/dev/vda3' rather than mmcblk0. I've updated the wiki 
to use the label ( root=LABEL=_/ ) , and its indeed working without specifying the 
dtb. 

Thanks!

Paul

> 
> > 
> > - Cole
> > 
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