Question about boot ARM guest on Arndale

Question about boot ARM guest on Arndale

[yan ren]

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Hi all,

Recently, i tried to boot ARM guest on my Arndale following the link
http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/Arndale.
But i meet several issues:
1. The CPU frequency  in dom0 cannot reach 1.7G. I ran some workload, it
seems the cpu frequency in dom0 is keep in 1G which in native is 1.7G. BTW,
there is no cpu frequency in /sys/device/system/cpu/cpu0/. bugs?
2. I boot the guest with the same file system as host(download from
linaro.org with ubuntu version). But i cannot run many command inside
guest: like dd, dmesg. It always shows illegal instruction when run those
command.
3. I compared the CPU info with host. It shows the guest doesn't have VFP
feature. Is it true?
4. Cannot see many devices via lsusb in dom0. Like usb NIC is missing in
dom0. What's the wrong?
5. The dom0_mem parameter in dts table cannot take affect. I changed it to
256M, but still see 512M after dom0 boot up.

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Re: Question about boot ARM guest on Arndale

[Ian Campbell]

On Mon, 2013-07-29 at 14:52 +0800, yan ren wrote:
> Hi all,
> 
> Recently, i tried to boot ARM guest on my Arndale following the link
> http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/Arndale.
> But i meet several issues:
> 1. The CPU frequency  in dom0 cannot reach 1.7G. I ran some workload,
> it seems the cpu frequency in dom0 is keep in 1G which in native is
> 1.7G. BTW, there is no cpu frequency in /sys/device/system/cpu/cpu0/.
> bugs?

CPU frequency scaling is not something we have considered yet. It would
likely need to be done at the hypervisor level and not by dom0. We have
a similar scheme on x86.

> 2. I boot the guest with the same file system as host(download from
> linaro.org with ubuntu version). But i cannot run many command inside
> guest: like dd, dmesg. It always shows illegal instruction when run
> those command.

This might relate to the lack of VFP which you go on to mention. We've
seen something like this in past when VFP was inadvertently disabled.

> 3. I compared the CPU info with host. It shows the guest doesn't have
> VFP feature. Is it true?

That should work, I don't think we are deliberately hiding or disabling
VFP for guests. I'm not sure where this bug could be though.

> 4. Cannot see many devices via lsusb in dom0. Like usb NIC is missing
> in dom0. What's the wrong?
> 5. The dom0_mem parameter in dts table cannot take affect. I changed
> it to 256M, but still see 512M after dom0 boot up.

Did you recompile the DTB and rebuild the hypervisor? I sometimes find
that changing the file referenced by CONFIG_DTB_FILE doesn't cause a
rebuild. I usually "rm xen/arch/arm/dtb.o" to be.

Ian

Re: Question about boot ARM guest on Arndale

[yan ren]

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Thanks for your explanation.

Is there any available guest image that i can download for using? I can do
nothing because of the illegal instruction issue. If there is a guest image
that using armel complier, i think it should be ok for me to try.

2013/7/29 Ian Campbell <Ian.Campbell@citrix.com>

> On Mon, 2013-07-29 at 14:52 +0800, yan ren wrote:
> > Hi all,
> >
> > Recently, i tried to boot ARM guest on my Arndale following the link
> > http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions/Arndale.
> > But i meet several issues:
> > 1. The CPU frequency  in dom0 cannot reach 1.7G. I ran some workload,
> > it seems the cpu frequency in dom0 is keep in 1G which in native is
> > 1.7G. BTW, there is no cpu frequency in /sys/device/system/cpu/cpu0/.
> > bugs?
>
> CPU frequency scaling is not something we have considered yet. It would
> likely need to be done at the hypervisor level and not by dom0. We have
> a similar scheme on x86.
>
> > 2. I boot the guest with the same file system as host(download from
> > linaro.org with ubuntu version). But i cannot run many command inside
> > guest: like dd, dmesg. It always shows illegal instruction when run
> > those command.
>
> This might relate to the lack of VFP which you go on to mention. We've
> seen something like this in past when VFP was inadvertently disabled.
>
> > 3. I compared the CPU info with host. It shows the guest doesn't have
> > VFP feature. Is it true?
>
> That should work, I don't think we are deliberately hiding or disabling
> VFP for guests. I'm not sure where this bug could be though.
>
> > 4. Cannot see many devices via lsusb in dom0. Like usb NIC is missing
> > in dom0. What's the wrong?
> > 5. The dom0_mem parameter in dts table cannot take affect. I changed
> > it to 256M, but still see 512M after dom0 boot up.
>
> Did you recompile the DTB and rebuild the hypervisor? I sometimes find
> that changing the file referenced by CONFIG_DTB_FILE doesn't cause a
> rebuild. I usually "rm xen/arch/arm/dtb.o" to be.
>
> Ian
>
>

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Re: Question about boot ARM guest on Arndale

[Julien Grall]

On 07/29/2013 11:36 AM, yan ren wrote:
> Thanks for your explanation.
> 
> Is there any available guest image that i can download for using? I can
> do nothing because of the illegal instruction issue. If there is a guest
> image that using armel complier, i think it should be ok for me to try.

I'm currently using a rootfs with busybox for the guest and it works fine.

-- 
Julien

Re: Question about boot ARM guest on Arndale

[yan ren]

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Thanks.

BTW: Can you tell me the link to download the ARM datasheet which cover the
visualization technology. I searched it in cortex-A15 spec, but got nothing
about virtualization.


2013/7/29 Julien Grall <julien.grall@citrix.com>

> On 07/29/2013 11:36 AM, yan ren wrote:
> > Thanks for your explanation.
> >
> > Is there any available guest image that i can download for using? I can
> > do nothing because of the illegal instruction issue. If there is a guest
> > image that using armel complier, i think it should be ok for me to try.
>
> I'm currently using a rootfs with busybox for the guest and it works fine.
>
> --
> Julien
>
>

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Re: Question about boot ARM guest on Arndale

[Julien Grall]

On 07/31/2013 04:01 AM, yan ren wrote:
> Thanks.
> 
> BTW: Can you tell me the link to download the ARM datasheet which cover
> the visualization technology. I searched it in cortex-A15 spec, but got
> nothing about virtualization.

The virtualization is covered by the ARMv7 datasheet:
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0406c/index.html

-- 
Julien