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

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2014-06-11 at 14:54 +0100, Jeenu Viswambharan wrote:
> It turned out to be a GCC 4.6 issue where the offset of vcpu inside
> struct domain was wrongly generated as 0xe4 while it's 0xf8. I almost
> forgot the recommendation to use GCC 4.8 in the Wiki. It goes past that
> with 2014.04 tool chain from Linaro. My bad!

You mean the contents of asm-offset.h was wrong or something else?

I routinely use Debian's gcc 4.6.3 to build Xen and I've not seen this.
Perhaps it's an issue with your specific build of gcc?

> Xen is now launching DOM0. But next issue I'm now facing is that Linux
> refusing to run when loaded at 0xa0008000 - it panics and complains
> about failing to allocate memory in mm/memblock.c:memblock_alloc_base().
> FWIW, I've built the kernel v3.14 with vexpress_defconfig and enabled
> Xen and highmem support. The kernel however is happy to boot when loaded
> at 0x80008000 (without Xen). The same with Xen though, the kernel
> reports 'uncompression error'.
> 
> It's little to do with Xen, but are there any other options required to
> be enabled in the DOM0 Kernel to run from 0xa0008000?

Your kernel needs to be relocatable. I'm not 100% which option that is
(perhaps CONFIG_ARM_PATCH_PHYS_VIRT) but if you build a multiplatform
kernel (CONFIG_ARCH_MULTIPLATFORM) it certainly will be.

> Also could you tell me at what point Xen jumps to guest entry? I tried
> break at the eret instruction following the label return_to_hypervisor,
> but the break point doesn't seem to hit.

It should, that's the right place.

Ian.


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