Re: Question about xen and Rasp 4B

[Jukka Kaartinen <jukka.kaartinen@xxxxxxxxxx>]

On 3.2.2021 2.18, Stefano Stabellini wrote:
> On Tue, 2 Feb 2021, Jukka Kaartinen wrote:
> > Hi Roman,
> >
> > > > >
> > > > Good catch.
> > > > GPU works now and I can start X! Thanks! I was also able to create domU
> > > > that runs Raspian OS.
> > > This is very interesting that you were able to achieve that - congrats!
> > >
> > > Now, sorry to be a bit dense -- but since this thread went into all
> > > sorts of interesting
> > > directions all at once -- I just have a very particular question: what is
> > > exact
> > > combination of versions of Xen, Linux kernel and a set of patches that went
> > > on top that allowed you to do that? I'd love to obviously see it
> > > productized in Xen
> > > upstream, but for now -- I'd love to make available to Project EVE/Xen
> > > community
> > > since there seems to be a few folks interested in EVE/Xen combo being able
> > > to
> > > do that.
> > I have tried Xen Release 4.14.0, 4.14.1 and master (from week 4, 2021).
> >
> > Kernel rpi-5.9.y and rpi-5.10.y branches from
> > https://github.com/raspberrypi/linux
> >
> > and
> >
> > U-boot (master).
> >
> > For the GPU to work it was enough to disable swiotlb from the kernel(s) as
> > suggested in this thread.
> How are you configuring and installing the kernel?
>
> make bcm2711_defconfig
> make Image.gz
> make modules_install
>
> ?
>
> The device tree is the one from the rpi-5.9.y build? How are you loading
> the kernel and device tree with uboot? Do you have any interesting
> changes to config.txt?
>
> I am asking because I cannot get to the point of reproducing what you
> are seeing: I can boot my rpi-5.9.y kernel on recent Xen but I cannot
> get any graphics output on my screen. (The serial works.) I am using the
> default Ubuntu Desktop rpi-install target as rootfs and uboot master.
This is what I do:

make bcm2711_defconfig
cat "xen_additions" >> .config
make Image  modules dtbs

make INSTALL_MOD_PATH=rootfs modules_install
depmod -a

cp arch/arm64/boot/dts/broadcom/bcm2711-rpi-4-b.dtb boot/
cp arch/arm64/boot/dts/overlays/*.dtbo boot/overlays/

config.txt:

[pi4]
max_framebuffers=2
enable_uart=1
arm_freq=1500
force_turbo=1

[all]
arm_64bit=1
kernel=u-boot.bin

start_file=start4.elf
fixup_file=fixup4.dat

# Enable the audio output, I2C and SPI interfaces on the GPIO header
dtparam=audio=on
dtparam=i2c_arm=on
dtparam=spi=on

# Enable the FKMS ("Fake" KMS) graphics overlay, enable the camera firmware
# and allocate 128Mb to the GPU memory
dtoverlay=vc4-fkms-v3d,cma-64
gpu_mem=128

# Comment out the following line if the edges of the desktop appear outside
# the edges of your display
disable_overscan=1


boot.source:
setenv serverip 10.42.0.1
setenv ipaddr 10.42.0.231
tftpb 0xC00000 boot2.scr
source 0xC00000

boot2.source:
tftpb 0xE00000 xen
tftpb 0x1000000 Image
setenv lin_size $filesize

fdt addr ${fdt_addr}
fdt resize 1024

fdt set /chosen xen,xen-bootargs "console=dtuart dtuart=serial0 
sync_console dom0_mem=1024M dom0_max_vcpus=1 bootscrub=0 vwfi=native 
sched=credit2"
fdt mknod /chosen dom0

# These will break the default framebuffer@3e2fe000 that
# is the same chosen -node.
#fdt set /chosen/dom0 \#address-cells <0x2>
#fdt set /chosen/dom0 \#size-cells <0x2>

fdt set /chosen/dom0 compatible "xen,linux-zimage" "xen,multiboot-module"
fdt set /chosen/dom0 reg <0x1000000 0x${lin_size}>

fdt set /chosen xen,dom0-bootargs "dwc_otg.lpm_enable=0 console=hvc0 
earlycon=xen earlyprintk=xen root=/dev/sda4 elevator=deadline rootwait 
fixrtc quiet splash"
setenv fdt_high 0xffffffffffffffff

fdt print /chosen

#xen
booti 0xE00000 - ${fdt_addr}