Re: [Xen-users] Xen 4.13 and Raspberry Pi4

[André Przywara <andre.przywara@xxxxxxx>]

On 26/03/2020 09:18, Julien Grall wrote:

Hi,

> On 26/03/2020 00:20, marcos.ata1983@xxxxxxxxx wrote:
>>
>> Em 24/03/2020 08:05, Julien Grall escreveu:
>>>
>>>
>>> On 24/03/2020 01:19, marcos.ata1983@xxxxxxxxx wrote:
>>>> Hi,
>>>
>>> Hello,
>>>
>>>> On *https://wiki.xenproject.org/wiki/Xen_Project_4.13_Feature_List*
>>>> I read that "Xen 4.13 also supports Hygon Dhyana 18h processor
>>>> family, *Raspberry Pi4* and Intel AVX512."
>>>>
>>>> So I try to install Xen Project from source (xen-4.13.0.tar.gz) on
>>>> my Raspberry Pi 4 4GB (with Raspbian Buster Lite):
                                 ^^^^^^^^
This might be a problem.
I am not sure we really support this crippled userland (ARMv6 +
hardfloat) for Xen.
Since the hardware virtualisation that Xen relies on was introduced in
ARMv7 only, ARMv6 was never a supported platform.

I guess the statement about "Raspberry Pi4" support in the release notes
applies purely to the hardware, as in: The Xen hypervisor is able to
boot on the board - at least that is all I tested.
This is mentioned because former RPi models (<= 3) could not run Xen due
to the missing GIC interrupt controller, which is now fixed in the RPi4.

That being said you could try to use any of the proper 64-bit
distributions for the RPi4 out there, at least that should fix your
compilation problems.
If and how they support installing the hypervisor is another issue. If
the boot process uses EFI (and thus grub), it should work, but if the
distribution relies on the RaspberryPi foundation boot process, I don't
see how we could load both Xen and Dom0 easily.

To your particular problem:

>>>>
>>>> *./configure* its OK
>>>>
>>>> But *make world *or *make dist *got the error message:
>>>>
>>>>
>>>> /tmp/cccDG1wU.s: Assembler messages:
>>>> /tmp/cccDG1wU.s:205: Error: selected processor does not support
>>>> `dmb' in ARM mode

"dmb" as an *instruction* is only supported on ARMv7, on ARMv6 it's a
system register write. I guess the Raspbian compiler is configured to
generate ARMv6-hf compatible code, so does not support the instruction.

Were you able to compile the hypervisor (make xen)? I think we fix this
issue there by forcing v7 support in the Makefiles, which we need anyway
for the hardware virtualisation code.

I am not sure if it's worth fixing this for the userland parts as well.
Clearly Xen can only run on >= ARMv7 hardware, so we might add a flag to
the compiler to enforce this?

Cheers,
Andre.

>>>> /tmp/cccDG1wU.s:227: Error: selected processor does not support
>>>> `dmb' in ARM mode
>>>> /tmp/cccDG1wU.s:268: Error: selected processor does not support
>>>> `dmb' in ARM mode
>>>> /tmp/cccDG1wU.s:289: Error: selected processor does not support
>>>> `dmb' in ARM mode
>>>> make[5]: ***
>>>> [/tmp/xen-4.13.0/tools/xenstore/../../tools/Rules.mk:213:
>>>> xenstored_domain.o] Error 1
>>>> make[5]: Leaving directory '/tmp/xen-4.13.0/tools/xenstore'
>>>> make[4]: *** [/tmp/xen-4.13.0/tools/../tools/Rules.mk:237:
>>>> subdir-install-xenstore] Error 2
>>>> make[4]: Leaving directory '/tmp/xen-4.13.0/tools'
>>>> make[3]: *** [/tmp/xen-4.13.0/tools/../tools/Rules.mk:232:
>>>> subdirs-install] Error 2
>>>> make[3]: Leaving directory '/tmp/xen-4.13.0/tools'
>>>> make[2]: *** [Makefile:73: install] Error 2
>>>> make[2]: Leaving directory '/tmp/xen-4.13.0/tools'
>>>> make[1]: *** [Makefile:134: install-tools] Error 2
>>>> make[1]: Leaving directory '/tmp/xen-4.13.0'
>>>> make: *** [Makefile:172: world] Error 2
>>>
>>> This seems to suggest the compiler used is not behaving as Xen
>>> expects. Would you mind to give more details on the compiler used?
>> ii  bcc 0.16.17-3.3                          armhf        16-bit x86 C
>> compiler
>> ii  device-tree-compiler 1.4.7-3+rpt1                        
>> armhf        Device Tree Compiler for Flat Device Trees
>> ii  g++ 4:8.3.0-1+rpi2                       armhf        GNU C++
>> compiler
>> ii  g++-8 8.3.0-6+rpi1                         armhf        GNU C++
>> compiler
>> ii  gcc 4:8.3.0-1+rpi2                       armhf        GNU C compiler
>> ii  gcc-8 8.3.0-6+rpi1                         armhf        GNU C
>> compiler
>> ii  libllvm9:armhf 1:9.0.1-6+rpi1~bpo10+1               armhf       
>> Modular compiler and toolchain technologies, runtime library
>> ii  libluajit-5.1-2:armhf 2.1.0~beta3+dfsg-5.1                
>> armhf        Just in time compiler for Lua - library version
>> ii  libluajit-5.1-common 2.1.0~beta3+dfsg-5.1                
>> all          Just in time compiler for Lua - common files
>> ii  libxkbcommon0:armhf 0.8.2-1                             
>> armhf        library interface to the XKB compiler - shared library
>> ii  luajit 2.1.0~beta3+dfsg-5.1                 armhf        Just in
>> time compiler for Lua programming language version 5.1
>> ii  ocaml-compiler-libs 4.05.0-11+rpi1                      
>> armhf        OCaml interpreter and standard libraries
>>>
>>>>
>>>>
>>>> Can someone help me? Its really possible to install Xen on Raspberry
>>>> Pi 4?
>>> You may want to have a look at
>>> https://github.com/dornerworks/xen-rpi4-builder.
>>
>> I tried (I gave up on the slow and inconsistent download of
>> gcc-arm-8.3-2019.03-x86_64-aarch64-linux-gnu.tar.xz).
>>
>> Anyway my question is: does Xen Project 4.13 support Raspberry Pi4?,
>> if so, maybe it was a good idea a how-to with dependencies, etc.
> 
> Andre and Stewart (in CC) worked on the RPI4 port. They may have a
> pointer to instructions rather than a script.
> 
> As an aside note, if there are any instructions, can they be added on
> the wiki [1]?
> 
> Cheers,
> 
> [1] https://wiki.xenproject.org/wiki/Xen_ARM_with_Virtualization_Extensions
> 


_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-users