Re: [Xen-devel] pvgrub2 for ARM

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

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On 06.11.2013 14:25, Ian Campbell wrote:
> On Wed, 2013-11-06 at 14:00 +0100, Vladimir 'φ-coder/phcoder' Serbinenko
> wrote:
>> Hello, all. I've ported grub2 to x86_64-xen and i386-xen (PAE only). How
>> big is the difference between ARM and i386 when seen as pv guest?
> 
> Very. Xen on ARM uses hardware functionality for second stage paging, so
> there is far less porting to do.
> 
Well doesn't matter much for GRUB as we change paging only at init,
before handoff and to init vfb. What about drivers?
>> I have an ARM here but it's a raspberry pi, so no support for xen. Are there
>> machines for under $100 on which xen runs?
> 
> The current platforms are listed on
> http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions. The one
> which is sub $100 is the Allwinner sunxi based stuff. The native Linux
> support is community driven by the linux-sunxi.org folks and is
> progressing nicely.
> 
> I've got a cubieboard2 (A20 based, <$100) which is a promising platform.
> I've mostly been trying to get (native) SATA going, so my Xen
> experiments are a bit lightweight, but it does boot. Bamvor has reported
> success with using the MMC and documented it on the wiki. I think he's
> using an A31 based STB of some sort.
> 
Thanks for info, I'll look into it.
>> What's with 64-bit ARM?
> 
> TBH I thought the GRuB On ARM stuff was mainly targeting 64-bit (at
> least within Linaro). Do you have native grub on 32-bit ARM already
> then?
> 
GRUB on 32-bit ARM works. We have currently 2 ports:
arm-uboot:
I've tested it myself on Raspberry pi with U-boot and in qemu (not sure
which machine right now, I think vexpress) with u-boot
arm-efi:
Apparently works but have never been able to test it myself.
> As far as 64-bit hardware goes you will have a struggle finding any at
> all right now, nevermind for under $100.
> 
> We should at some point be able to support the freely (as in beer)
> available Foundation model, but we don't right now.
> 
>> Alternatively, I'll probably go for Google HP chromebook 11.
> 
> I don;t know about this one, but previous chromebooks have proved a pain
> to get Xen onto, too hard to debug anything on them...
> 
You need to solder couple of pins and connect them to raspberry pi. Or
get debug board.
>> Or may I have access to some server where I'd be able to run VMs with my
>> kernel (GRUB) and HDD?
> 
> I'm afraid we don't here at least.
> 
Pity, sth like this would aid OS porters greatly.


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