Re: [Xen-devel] [PATCH] [Xen] Check FADT's signature

[Stefan Berger <stefanb@xxxxxxxxxx>]

> Okay, please try tip of staging tree (c/s 15773).

This solves the problem with mapping ACPI memory and
the timer address is read correctly. Thanks!

  Stefan

> 
>  -- Keir
> 
> On 24/8/07 07:19, "Stefan Berger" <stefanb@xxxxxxxxxx>
wrote:

> 
> xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 08/10/2007 09:15:57
PM:
> 
> > A good debugging approach will be to write a function that walks
the
> > pagetables for that virtual address and prints the PTE that maps
it.
> > Scatter calls to this function between acpi_boot_table_init()
and 
> > acpi_boot_init() and hence narrow down exactly where the PTE
is 
> > getting zapped. 
> 
> What is happening is that the pl1e pointer used for mapping the ACPI
> table entry changes between the calls before paging_init() and 
> after. The l1_pgentry_t that is used before paging_init() correctly
> shows that the page is present whereas the one used after indicates
> that the page is not present. Then when the ACPI table is mapped 
> after paging_init() the tlb is not flushed and wrong information is
read. 
> 
>   Stefan 
> 
> > 
> >  -- Keir
> > 
> > On 10/8/07 19:21, "Keir Fraser" <keir@xxxxxxxxxxxxx>
wrote:
> 
> > On 10/8/07 18:00, "Stefan Berger" <stefanb@xxxxxxxxxx>
wrote:
> 
> > (XEN) map_pages_to_xen : 3533          
                     
    
> > (that's the line number)
> > (XEN) 0xfff9b000 was NOT present. 
> > 
> > Something between (*) and here seems to trash this presence flag.
> > paging_init() and many others lie in between the upper call and
this
> > one here. Could be a side effect of this? Maybe that tlb flush
at 
> > the right place in one of these functions would solve the problem?
> > 
> > Yes, this now looks likely and that’s rather scary. We’ll go
after 
> > this next week. 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@xxxxxxxxxxxxxxxxxxx
> > http://lists.xensource.com/xen-devel
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