Re: [Xen-devel] [GSoC] Xen on ARM: create multiple guests from device tree

[Luca Miccio <lucmiccio@xxxxxxxxx>]

Hi Stefano and Julien,

> Il giorno 22 mar 2017, alle ore 22:38, Stefano Stabellini 
> <sstabellini@xxxxxxxxxx> ha scritto:
> 
> Hi Luca,
> 
> please don't use HTML emails.
> 
> 
Sorry for that.

> On Wed, 22 Mar 2017, Julien Grall wrote:
>> On 22/03/2017 19:45, Luca Miccio wrote:
>>> Hi Stefano,
>> 
>> Hello Luca,
>> 
>>> aarch64-linux-gnu-gcc  -DCNTFRQ=0x01800000-DUART_BASE=0x1c090000
>>> -DSYSREGS_BASE=0x1c010000 -DGIC_DIST_BASE=0x2c001000
>>> -DGIC_CPU_BASE=0x2c002000 -c -o boot.xen.o boot.S -DXEN
>>> aarch64-linux-gnu-gcc  -DPHYS_OFFSET=0x80000000 -DMBOX_OFFSET=0xfff8
>>> -DBOOT=boot.xen.o -DXEN_OFFSET=0xA00000 -DKERNEL_OFFSET=0x80000
>>> -DFDT_OFFSET=0x08000000 -DFS_OFFSET=0x10000000 -DXEN=Xen -DKERNEL=Image
>>> -DFILESYSTEM=filesystem.cpio.gz -E -P -C -o model.xen.lds model.lds.S
>>> aarch64-linux-gnu-gcc  -DCNTFRQ=0x01800000-DUART_BASE=0x1c090000
>>> -DSYSREGS_BASE=0x1c010000 -DGIC_DIST_BASE=0x2c001000
>>> -DGIC_CPU_BASE=0x2c002000 -c -o boot.o boot.S
>>> aarch64-linux-gnu-gcc  -DPHYS_OFFSET=0x80000000 -DMBOX_OFFSET=0xfff8
>>> -DBOOT=boot.o -DKERNEL_OFFSET=0x80000 -DFDT_OFFSET=0x08000000
>>> -DFS_OFFSET=0x10000000 -DKERNEL=Image -DFILESYSTEM=filesystem.cpio.gz -E
>>> -P -C -o model.lds model.lds.S
>>> aarch64-linux-gnu-ld -o xen-system.axf --script=model.xen.lds
>>> aarch64-linux-gnu-ld: section .xen LMA
>>> [0000000080a00000,0000000080ac814f] overlaps section .kernel LMA
>>> [0000000080080000,0000000080f009ff]
>>> Makefile:78: set di istruzioni per l'obiettivo "xen-system.axf" non riuscito
>>> make: *** [xen-system.axf] Errore 1\
>>> 
>>> Clearly there is a problem with the offset of xen section but i can't
>>> figure out how to solve it.
>> 
>> I would recommend to use the latest version of bootwrapper which is now
>> including support for Xen. I haven't yet updated the wiki with the runes
>> but here a quick summary of the step I am using:
>> 
>> * Building bootwrapper
>> 
>> 42sh> git clone 
>> git://git.kernel.org/pub/scm/linux/kernel/git/mark/boot-wrapper-aarch64.git
>> 42sh> autoreconf -i
>> 42sh> ./configure --host=aarch64-linux-gnu --with-kernel-dir=<kernel-dir> 
>> --with-dtb=<dtb> \
>> --with-cmdline="console=hvc0 earlycon=pl011,0x1c090000 root=/dev/vda rw" 
>> --enable-psci \
>> --with-xen-cmdline="dtuart=serial0 console=dtuart no-bootscrub 
>> dom0_mem=512M" \
>> --with-xen=<xen-bin> --with-cpu-ids=0,1,2,3
>> 42sh> make
>> 
>> Where:
>>  * <kernel-dir> is the path to the kernel repository
>>  * <dtb> is the path to the device-tree. I am using the one shipped with 
>> Linux
>>    in arch/arm64/boot/dts/arm/foundation-armv8.dtbs
>>    It will be built if you did make all in Linux
>>  * <xen-bin> is the path to Xen binary (xen/xen in the repo)
>> 
>> * Command line for the foundation model
>> 42sh> Foundation_Platform --image=<image> --block-device=<rootfs> --cores=4
>> 
>> Where:
>>  * <image> is the path to xen-system.axf produced by bootwrapper
>>  * <rootfs> is the patch to your rootfs
>> 
>> Let me know if you need more details.
> 
> Thanks Julien, I successfully booted Xen and Linux following these
> steps. I quickly updated the wiki.
> 
> Luca, I took me a while to figure out that for root=/dev/vda to work
> properly, Linux requires not just all the filesystem and virtio options
> enabled in the kernel config, but also CONFIG_VIRTIO_MMIO=y. With that,
> you should be able to boot Xen, Linux and mount the root filesystem. If
> you download one of the Ubuntu arm64 cloud images, the root device will
> be /dev/vda1.

First of all, thank you for your help.

I think that i keep on doing somenthing wrong because now the bootwrapper 
produces
with no errors the xen-system.axf  with the configuration that Julien provided. 
But when i launch the emulator it simply stops at:
(XEN) Bringing up CPU1

To help you understand, this is what i have done:
- First i compiled the xen source with the following command:
$ make dist-xen XEN_TARGET_ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- 
CONFIG_EARLY_PRINT=fastmodel
( I am using the staging branch)

- Get the linux source with git: 
$ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git

-Checkout on the v4.4 branch 

- Follow the steps described in the blog and, as you said, i set in my .config 
file:
 CONFIG_VIRTIO=y
 CONFIG_VIRTIO_MMIO=y
 CONFIG_VIRTIO_BLK=y
I also checked all the filesystem and virtio options. 

- Compile the linux kernel with the toolchain:
$ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- all (to get also the .dtb 
file)

- Configured the bootwrapper with the command that Julian wrote and then 
launched the 
foundation model with the simple command:
$ Foundation_Platform --image=/path/to/the/xen-system.axf 
--block-device=xenial-server-cloudimg-arm64.img --cores=4

The image was downloaded at : 
https://cloud-images.ubuntu.com/releases/16.04/release/

But, as I said, the emulator blocks at boot. I tried different rootfs images 
and i have configured the root device
properly to /dev/vda1.

Maybe my kernel configuration is wrong?

Thank you,
Luca


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