Re: [Xen-ia64-devel] Memory problem with mini-os

[Dietmar Hahn <dietmar.hahn@xxxxxxxxxxxxxxxxxxx>]

Am Montag, 2. Oktober 2006 09:57 schrieb Tristan Gingold:
> Le Lundi 02 Octobre 2006 09:35, Dietmar Hahn a écrit :
> > Hi,
> >
> > after my vacation I switched from xen-ia64 change-set 11039 to 11635.
> > And now I have a problem with my mini-os executing the efi/pal code
> > (currently the getTime - function from efi). Every time the function gets
> > called I get an trap 22 (Instruction access rights vector). The strange
> > thing is that the trap also occurs if I don't do the mapping of the pal
> > code.
> > I inserted some trace messages in vcpu_itr_i() in xen to see all
> > parameters. But it looks ok.
> > For a test I removed the call of in ia64_itr() in efi_map_pal_code() in
> > the linux code and nevertheless efi_gettimeofday() runs fine (linux as
> > domU). It seems, there is another tlb entry for this page.
> > I saw that the pal/efi stuff was reorganized in the new change-set.
> > Can anybody give me a hint where to look in the memory handling or do
> > some trace messages! I'm currently still not familiar enough with this
> > stuff.
>
> Hi,
>
> After your comments I have reorganized fw memory.
To much honour ;-),

> The PAL/SAL/EFI firmware is now between 0 and 4Kb.
> ACPI and system tables are between 4Kb and 12Kb.
> Because the size is very small there might be an entry in the TLB even
> without the itr.
>
> I think you should start debugging gu understand where and why the fault
> occurs.  You may modify Xen to disp more details when a fault is reflected.
>
> Tristan.

I think I understand the problem!
I use the Alternate Data TLB trap for the data translations needed for 
efi/pal/sal/acpi. These translations are done with access rights RW. In XEN 
ITC and DTC seem to be unified, so the data tlb entry is used for the 
translation of the efi-code. And there is no X bit set -> trap 22.
If I set RWX for the access rights of the data translations all runs well.
The better way is a ptc.l before mapping of the pal code via a itr.i!
Thanks.

DIetmar.

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