[Pkg-xen-devel] What's missing for arm64 Xen boot with FDT via Grub in Debian Bullseye?
Alex Bennée
alex.bennee at linaro.org
Fri May 28 18:27:52 BST 2021
Julien Grall <julien at xen.org> writes:
> On 28/05/2021 13:49, Alex Bennée wrote:
>> Hi,
>
> Hi Alex,
>
>> I'm currently trying to pull together the threads for booting Xen on
>> Debian. I'm currently doing this within QEMU's TCG emulation and the
>> "virt" machine model:
>> -machine type=virt,virtualization=on,gic-version=3 \
>> -cpu max,pauth-impdef=on
>> with the firmware on my Ubuntu machine:
>> -drive
>> if=pflash,file=/usr/share/AAVMF/AAVMF_CODE.fd,format=raw,readonly=on
>> -drive if=pflash,file=$HOME/images/AAVMF_VARS.fd,format=raw
>> (qemu-efi-aarch64 Version: 0~20180205.c0d9813c-2ubuntu0.3)
>> When booting this way I get the Grub menu and Xen is loaded by Grub
>> but
>> falls over later:
>> (XEN) MODULE[0]: 00000000f5869000 - 00000000f59b60c8 Xen
>> (XEN) MODULE[1]: 000000013857d000 - 0000000138580000 Device Tree
>> (XEN) MODULE[2]: 00000000f73a1000 - 00000000f8da0780 Kernel
>> (XEN) MODULE[3]: 00000000f59b7000 - 00000000f739f99b Ramdisk
>> (XEN)
>> (XEN) CMDLINE[00000000f73a1000]:chosen placeholder root=UUID=435201aa-c5cf-4e7a-8107-5eef28844188 ro console=hvc0
>> (XEN)
>> (XEN) Command line: placeholder dom0_mem=2G loglvl=all guest_loglvl=all no-real-mode edd=off
>> (XEN) parameter "placeholder" unknown!
>> (XEN) parameter "no-real-mode" unknown!
>> (XEN) parameter "edd" unknown!
>> (XEN) Domain heap initialised
>> (XEN) Booting using Device Tree
>> (XEN) Platform: Generic System
>> (XEN)
>> (XEN) ****************************************
>> (XEN) Panic on CPU 0:
>> (XEN) Unable to find a compatible timer in the device tree
>> (XEN) ****************************************
>> It seems like there are bits of the DT missing. I can however
>> successfully boot Xen with the Linux guest using the guest-loader device
>> and bypassing the firmware/boot code step. This gives:
>> (XEN) MODULE[0]: 0000000040200000 - 000000004034d0c8 Xen
>> (XEN) MODULE[1]: 0000000048000000 - 0000000048100000 Device Tree
>> (XEN) MODULE[2]: 0000000046000000 - 0000000046eb2200 Kernel
>> (XEN)
>> (XEN) CMDLINE[0000000046000000]:chosen root=/dev/sda2 console=hvc0 earlyprintk=xen
>> (XEN)
>> (XEN) Command line: dom0_mem=4G dom0_max_vcpus=4
>> (XEN) Domain heap initialised
>> (XEN) Booting using Device Tree
>> (XEN) Platform: Generic System
>> (XEN) Taking dtuart configuration from /chosen/stdout-path
>> (XEN) Looking for dtuart at "/pl011 at 9000000", options ""
>> Xen 4.15.1-pre
>> (XEN) Xen version 4.15.1-pre (alex.bennee@) (aarch64-linux-gnu-gcc (Debian 8.3.0-2) 8.3.0) debug=y Tue May 18 09:34:55 UTC 2021
>> (XEN) Latest ChangeSet:
>> (XEN) build-id: a50d8f03a1a15662ac7c4e5f73f2f544a6739df2
>> (XEN) Processor: 411fd070: "ARM Limited", variant: 0x1, part 0xd07, rev 0x0
>> (XEN) 64-bit Execution:
>> (XEN) Processor Features: 0000000001000222 0000000000000000
>> (XEN) Exception Levels: EL3:No EL2:64+32 EL1:64+32 EL0:64+32
>> (XEN) Extensions: FloatingPoint AdvancedSIMD GICv3-SysReg
>> (XEN) Debug Features: 0000000010305106 0000000000000000
>> (XEN) Auxiliary Features: 0000000000000000 0000000000000000
>> (XEN) Memory Model Features: 0000000000001124 0000000000000000
>> (XEN) ISA Features: 0000000000011120 0000000000000000
>> (XEN) 32-bit Execution:
>> (XEN) Processor Features: 00000131:10011001
>> (XEN) Instruction Sets: AArch32 A32 Thumb Thumb-2 Jazelle
>> (XEN) Extensions: GenericTimer
>> (XEN) Debug Features: 03010066
>> (XEN) Auxiliary Features: 00000000
>> (XEN) Memory Model Features: 10101105 40000000 01260000 02102211
>> (XEN) ISA Features: 02101110 13112111 21232042 01112131 00011142 00011121
>> (XEN) Using SMC Calling Convention v1.0
>> (XEN) Using PSCI v0.2
>> (XEN) SMP: Allowing 8 CPUs
>> (XEN) enabled workaround for: ARM erratum 832075
>> (XEN) enabled workaround for: ARM erratum 834220
>> (XEN) enabled workaround for: ARM erratum 1319367
>> (XEN) Generic Timer IRQ: phys=30 hyp=26 virt=27 Freq: 62500 KHz
>> (XEN) GICv3 initialization:
>> (XEN) gic_dist_addr=0x00000008000000
>> (XEN) gic_maintenance_irq=25
>> (XEN) gic_rdist_stride=0
>> (XEN) gic_rdist_regions=1
>> (XEN) redistributor regions:
>> (XEN) - region 0: 0x000000080a0000 - 0x00000009000000
>> (XEN) GICv3: 256 lines, (IID 0000043b).
>> (XEN) GICv3: CPU0: Found redistributor in region 0 @000000004001c000
>> Attempting to boot with acpi=on still sees Grub attempt to use DT to
>> boot the hypervisor. However selecting the kernel directly boots with
>> ACPI (which is a shame as I'd like to see what FDT it gets presented
>> with).
>
> ACPI is not built by default in Xen on Arm. You will need to select it
> from Kconfig and rebuild the hypervisor.
OK so I think what was happening is grub was always passing ACPI and
with Xen not built for it there was simply no DTB to process. Testing
with a ACPI build works for Bullseye.
Testing on Buster Xen does boot but hangs at:
(XEN) *** LOADING DOMAIN 0 ***
(XEN) Loading d0 kernel from boot module @ 00000000f7d2d000
(XEN) Loading ramdisk from boot module @ 00000000f304b000
(XEN) Allocating 1:1 mappings totalling 2048MB for dom0:
(XEN) BANK[0] 0x00000040000000-0x000000c0000000 (2048MB)
(XEN) Grant table range: 0x000000f2ef5000-0x000000f2f35000
(XEN) Allocating PPI 16 for event channel interrupt
(XEN) Loading zImage from 00000000f7d2d000 to 0000000040080000-0000000041264780
(XEN) Loading d0 initrd from 00000000f304b000 to 0x0000000048200000-0x000000004cee0c00
(XEN) Loading d0 DTB to 0x0000000048000000-0x000000004800027f
(XEN) Initial low memory virq threshold set at 0x4000 pages.
(XEN) Scrubbing Free RAM in background
(XEN) Std. Loglevel: All
(XEN) Guest Loglevel: All
(XEN) *** Serial input to DOM0 (type 'CTRL-a' three times to switch input)
(XEN) Freed 380kB init memory.
I'll need to update by build environment and rebuild for Bullseye to
check I can still start a new domain.
>
>> The full command line for booting via the guest-loader is:
>> ./qemu-system-aarch64 \
>> -machine virt,virtualization=on,gic-version=3 \
>> -cpu max,pauth-impdef=on \
>> -serial mon:stdio \
>> -netdev user,id=net1,hostfwd=tcp::2222-:22 \
>> -device virtio-net-pci,netdev=net1 \
>> -device virtio-scsi-pci \
>> -drive file=/dev/zvol/hackpool-0/debian-buster-arm64,id=hd0,index=0,if=none,format=raw \
>> -device scsi-hd,drive=hd0 \
>> -display none \
>> -m 16384 \
>> -kernel ~/lsrc/xen/xen.build.arm64-xen/xen/xen \
>> -append "dom0_mem=4G dom0_max_vcpus=4" \
>> -device guest-loader,addr=0x46000000,kernel=$HOME/lsrc/linux.git/builds/arm64/arch/arm64/boot/Image,bootargs="root=/dev/sda2 console=hvc0 earlyprintk=xen" \
>> -smp 8
>> So some questions:
>> - is Xen on arm64 tested on Debian Bullseye? If so what platform?
>
> I am using Debian Bullseye on QEMU and also the FVP. We are also using
> Debian in Osstest for all the testing (it is possible an older version
> of Debian).
>
>> - how do I tell Grub to do a straight FDT boot with the DT from the firmware?
>
> Is the firmware actually providing a DT? You could try to boot Xen
> from UEFI directly to confirm that.
>
> However, I vaguely recall that GRUB may only pass ACPI if it is provided.
>
>> - are there any missing pieces I should be aware of?
>
> Other than re-building Xen with ACPI=y, I am not aware of any issue to
> use Xen with Debian bullseye.
>
> Cheers,
--
Alex Bennée
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