[Skiboot] [PATCH v8 01/24] OPAL: Add OPAL boot entry address to device tree

Oliver O'Halloran oohall at gmail.com
Tue Jul 9 19:53:29 AEST 2019

On Fri, 2019-06-28 at 14:34 +0530, Vasant Hegde wrote:
> On 06/28/2019 06:18 AM, Nicholas Piggin wrote:
> > Vasant Hegde's on June 17, 2019 3:10 am:
> > > Needed for creating OPAL core file.
> > > 
> > > Sample output:
> > > --------------
> > >    sys/firmware/devicetree/base/ibm,opal # lsprop
> > >    ...
> > >    opal-boot-address
> > > 		 00000000 30002560
> > >    ...
> > 
> > Why is this needed? We can't derive it from the symbol table?

> Kernel needs this address to generate proper OPAL dump.

I looked at Hari's patches to try work out what a "proper dump"
is. Looks like we use this to create the AT_ENTRY note for the
opalcore which file. Sounds important, but I can't find where
the same happens for the Linux vmcore, so maybe it's not?

> We can read it
> from symbol table. But then kernel has to read OPAL symbol table and
> parse it to get the data.

You know... if we punted generating the opalcore to userspace rather
than doing it in the kernel this wouldn't be an issue ;)

> Hence I have added this property so that kernel can directly read DT
> to get entry address.

The value you're reading out of the DT is the value for the currently
running skiboot rather than the one that crashed so this fishy to begin

We have two architected entry points: fdt_entry at SKIBOOT_BASE+0x10
and hdat_entry at SKIBOOT_BASE+0x180. If you have to put this in the DT
then use one of those.


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