Re: [Xen-users] ARM: Xen on Vexpress

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

CCing Julien and Stefano who I think have both run Xen on vexpress

On Tue, 2014-06-03 at 18:11 +0100, Jeenu Viswambharan wrote:
> Hi,
> 
> I've built necessary files and setup uboot and board to boot Xen on
> Vexpress following the Wiki page. But what I see is u-boot going silent,
> presumably after it jumps to Xen. My logs are attached.

Jeenu, Which version of Xen are you building?

Skimming that wiki page it seems to be describing how to use an older
version of Xen (like 4.3 or early 4.4 development era) and not a modern
4.4 or 4.5 development hypervisor.

In particular I'm not sure it is referencing a u-boot which boots the
kernel in HYP mode (Xen used to carry a hacky workaround for thus, but
doesn't now) and the stuff about KERNEL_FLASH_ADDRESS (another
workaround for lack of a boot protocol which is no longer present) isn't
true any more either.

Julien/Stefano can you confirm and/or deny? I think Linaro tests on
vexpress so I suppose there are more modern steps somewhere?

> I've a couple of questions:
> 
>   - I've noticed from the Vexpress Wiki that the u-boot variable
>     xen_addr_r is set to 0x80400000, but the xen-uImage is built with
>     both load and entry addresses as 0x80200000. I also checked the
>     xen/xen.axf file (from which xen/xen is built), and its entry too is
>     0x80200000. I'm afraid to ask if this a typo/bit rot in the Wiki?

I'm not sure, but I think in general it is OK for these to differ,
u-boot will relocate from the load address to the address requested by
the header as part of booting. So long as it is in RAM and 2MB aligned I
don't think the actual address matters too much.

>     Anyway, I retried boot procedure with xen_addr_r set to 0x80200000
>     instead, but this time I got an UNDEF at instruction at 0x80200008
> 
>   - Are there any logs that I can enable in Xen so that I'd know what's
>     going on?

Are you building with "debug=y CONFIG_EARLY_PRINTK=vexpress" on your
make invocation? You will need to "make clean" if you add these now.
That should get you some output earlier.

Ian.


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