Re: BINIT and physical address

["Natalie Protasevich" <protasnb@gmail.com>]

On 8/14/07, Luck, Tony <tony.luck@intel.com> wrote:
> > Some help is needed with debugging of a hang.
> > A system hits BINIT once in a while and the processors are all
> > spinning on the address 0x00100002C00 and if the HT is off the address
> > becomes 0x0020000A80. This is a physical address captured on the bus
> > by analyser. How can this address be decoded to find out what are the
> > processors are spinning on?
>
> Natalie,
>
> The Linux kernel is typically loaded at physical address 0x400000 (64MB)
> in one continuous block.  If that address doesn't exist on your platform
> then elilo will get some other 64MB aligned address instead.  You may be
> able to tell what is the state on you machine by looking at the TLB 'TR'
> registers:
> $ cat /proc/pal/cpu0/tr_info
>
> Look at the mappings for ITR0 and DTR0 ... they map the kernel. I
> say 'may' because some older systems didn't report TR maps
> correctly.
>
> Kernel modules loaded after boot will be all over the place.  You
> can easily find the virtual addresses in use with:
> $ cat /proc/modules
> But there isn't a user-mode accessible way to convert them to
> physical addresses.  You could write a small loadable driver to
> do this.  It is unlikely that all the modules would end up with
> exactly the same physical addresses from one boot to the next,
> so you'll need to capture this information before the BINIT hits.
>
> You should also check whether the memory addresses in question
> were available for Linux to use.
> $ cat /proc/iomem
>
> Unless the addresses are marked as "System RAM" they wouldn't
> have been used by Linux ... so if you are spinning there, it
> is because they are part of firmware (PAL, SAL, EFI).
>
> -Tony
>
Thanks Tony and Bernhard, this was exactly what I was looking for. It
is not identity mapped and I suppose can get regions and ranges in
translation registers etc. Then after getting the modules mapping it's
a matter of running ITP...

--Natalie