Re: [Xen-ia64-devel] Community effort neededtocatch upwithxen-unstable

[John Byrne <john.l.byrne@xxxxxx>]

> So you're talking problem from when booting domU? You're right about the
> x86 behavior, but that's different on current ia64 model. Dan prefers to
> adopt a transparent virtualization mechanism, so minimal changes are
> required to touch common linux code. If we also place those system pages
> after the kernel image, you have to modify efi syb-system to ignore
> these pages.
>
> Currently I just put the last page allocated to xenU as the store page,
> not in the middle. But yes, there's still one problem in dom_fw_init,
> where all allocated pages are exposed to domain. Instead we should
> reserve the last page and let store page out of domain's scope. Check
> whether following changes solves your issue:
>
> diff -r 8799d14bef77 xen/arch/ia64/dom_fw.c
> --- a/xen/arch/ia64/dom_fw.c    Thu Aug 25 22:53:20 2005
> +++ b/xen/arch/ia64/dom_fw.c    Fri Sep  2 10:38:11 2005
> @@ -512,6 +512,11 @@
>                 return 0;
>         }
>  */
> +
> +       /* Last page is for xenstore, and not exported to domain */
> +       if (d != dom0)
> +               maxmem = (d->max_pages - 1) * PAGE_SIZE;
> +
>         memset(fw_mem, 0, fw_mem_size);
>
>  #ifdef XEN
>
> Thanks,
> Kevin
With all the various patches, things work fine and I get a login prompt.

I knew the x86 model was different, what I didn't know was what you did 
with this patch was legal. It looks to me as if you have the operating 
system accessing a page the VM really shouldn't let it have. I was 
trying to figure out how to reserve the page in the EFI memory map: add 
it to the end of the hypercall page or something. Maybe its fortunate I 
had to go home so you could come up with the more straightforward fix.
Spoke a little too soon, again. Looks like dom0 just crashed hard:

(XEN) +01+01Heartbeat... iip=f0000000040092d0,psr.i=0,pend=1
(XEN) +01ia64_fault: General Exception: IA-64 Reserved Register/Field 
fault (data access): reflecting 

I've no clue what the problem might be, things were idle. Still, things 
are better.
Thanks,

John




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