Re: Kernel OOPS and panic on boot in advantech watchdog init

[Jeremy Fitzhardinge]

Alan Cox wrote:
> Looks like yet another Xen bug
>   

No, we've been over this before.

>> [   30.328280] BUG: unable to handle kernel paging request at d6023220
>> [   30.332244] IP: [<c021f6f3>] xen_set_pte+0x3/0x10
>>     
>
> sc520 tries to make an ioremap to read 0xfffefcb0
>
>   
>> [   30.332244]  [<c037be42>] ioremap_page_range+0x1e2/0x280
>> [   30.332244]  [<c023d311>] __ioremap_caller+0x1e1/0x340
>>     
>
> The Xen glue should have either permitted the mapping or failed the
> ioremap attempt with NULL.

Xen glue doesn't get in at that level.  The first Xen knows about the
mapping is the attempt to set a pte with meaningless contents.

I still think the sc520 driver should make some rudimentary attempt to
see if its actually running on a relevant system (ie, an AMD Elan)
before creating iomappings.  I don't know if DMI, cpuid or some other
mechanism would be best though.

    J
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