Re: Xen 4.14.1 on RPI4: device tree generation failed

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Mon, 1 Feb 2021, Tamas K Lengyel wrote:
> On Mon, Feb 1, 2021 at 10:23 AM Tamas K Lengyel
> <tamas.k.lengyel@xxxxxxxxx> wrote:
> >
> > On Mon, Feb 1, 2021 at 12:54 AM Elliott Mitchell <ehem+xen@xxxxxxx> wrote:
> > >
> > > On Sun, Jan 31, 2021 at 10:06:21PM -0500, Tamas K Lengyel wrote:
> > > > With rpi-4.19.y kernel and dtbs
> > > > (cc39f1c9f82f6fe5a437836811d906c709e0661c) Xen boots fine and the
> > > > previous error is not present. I get the boot log on the serial with
> > > > just console=hvc0 from dom0 but the kernel ends up in a panic down the
> > > > line:
> > >
> > > > This seems to have been caused by a monitor being attached to the HDMI
> > > > port, with HDMI unplugged dom0 boots OK.
> > >
> > > The balance of reports seem to suggest 5.10 is the way to go if you want
> > > graphics on a RP4 with Xen.  Even without Xen 4.19 is looking rickety on
> > > RP4.
> > >
> > >
> > > On Sun, Jan 31, 2021 at 09:43:13PM -0500, Tamas K Lengyel wrote:
> > > > On Sun, Jan 31, 2021 at 8:59 PM Elliott Mitchell <ehem+xen@xxxxxxx> 
> > > > wrote:
> > > > >
> > > > > On Sun, Jan 31, 2021 at 06:50:36PM -0500, Tamas K Lengyel wrote:
> > > > > > On Sun, Jan 31, 2021 at 6:33 PM Elliott Mitchell 
> > > > > > <ehem+undef@xxxxxxx> wrote:
> > > > > > > Presently the rpixen script is grabbing the RPF's 4.19 branch, 
> > > > > > > dates
> > > > > > > point to that last being touched last year.  Their tree is at
> > > > > > > cc39f1c9f82f6fe5a437836811d906c709e0661c.
> > > > > >
> > > > > > I've moved the Linux branch up to 5.10 because there had been a fair
> > > > > > amount of work that went into fixing Xen on RPI4, which got merged
> > > > > > into 5.9 and I would like to be able to build upstream everything
> > > > > > without the custom patches coming with the rpixen script repo.
> > > > >
> > > > > Please keep track of where your kernel source is checked out at since
> > > > > there was a desire to figure out what was going on with the 
> > > > > device-trees.
> > > > >
> > > > >
> > > > > Including "console=hvc0 console=AMA0 console=ttyS0 console=tty0" in 
> > > > > the
> > > > > kernel command-line should ensure you get output from the kernel if it
> > > > > manages to start (yes, Linux does support having multiple consoles at 
> > > > > the
> > > > > same time).
> > > >
> > > > No output from dom0 received even with the added console options
> > > > (+earlyprintk=xen). The kernel build was from rpi-5.10.y
> > > > c9226080e513181ffb3909a905e9c23b8a6e8f62. I'll check if it still boots
> > > > with 4.19 next.
> > >
> > > So, their current HEAD.  This reads like you've got a problematic kernel
> > > configuration.  What procedure are you following to generate the
> > > configuration you use?
> > >
> > > Using their upstream as a base and then adding the configuration options
> > > for Xen has worked fairly well for me (`make bcm2711_defconfig`,
> > > `make menuconfig`, `make zImage`).
> > >
> > > Notably the options:
> > > CONFIG_PARAVIRT
> > > CONFIG_XEN_DOM0
> > > CONFIG_XEN
> > > CONFIG_XEN_BLKDEV_BACKEND
> > > CONFIG_XEN_NETDEV_BACKEND
> > > CONFIG_HVC_XEN
> > > CONFIG_HVC_XEN_FRONTEND
> > >
> > > Should be set to "y".
> >
> > Yes, these configs are all set the same way for all Linux builds by the 
> > script:
> >         make O=.build-arm64 ARCH=arm64
> > CROSS_COMPILE=aarch64-none-linux-gnu- bcm2711_defconfig xen.config
> >
> > I tried with both the rpi-5.10.y and rpi-5.9.y, neither boot up as
> > dom0. So far only 4.19 boots.
> 
> rpi-5.4.y boots but ends up in yet another different kernel panic:

That's an interesting error. However, I can tell you that I can boot
rpi-5.9.y just fine (without a monitor attached) with:

cd linux
KERNEL=kernel7l
make bcm2711_defconfig

As mentioned here:

https://www.raspberrypi.org/documentation/linux/kernel/building.md

and also taking the device tree from arch/arm64/boot/dts/broadcom/.