[Crash-utility] [PATCH] Crash-Utility: s390x: Auto-detect the correct MAX_PHYSMEM_BITS used in vmcore being analyzed.

[Dave Anderson]

----- Original Message -----

> > This would seem to be a little extreme.  If by chance CONFIG_SPARSEMEM
> > is not configured, or for that matter, in old pre-sparsemem kernels,
> > "mem_section" doesn't even exist as a symbol.  So there should be an
> > IS_SPARSEMEM() qualifier to prevent the FATAL session-ending error.
> > 
> > I'm waiting for an s390x reservation as we speak, and I'll change
> > (and test) the patch to do something like:
> > 
> >                if (IS_SPARSEMEM() && !set_s390x_max_physmem_bits())
> >                        error(FATAL, ...
> 
> Actually that won't suffice, because the POST_GDB init call is done
> before vm_init().  I'll add a new POST_VM case label to the s390x_init()
> switch statement, and move the set_s390x_max_physmem_bits() call
> there.

... which won't work either, because vm_init() calls sparse_mem_init()
which needs the MAX_PHYSMEM_BITS to be already set.

I guess we'll have to check for the existence of the mem_section array
and preemptively/redundantly make the STRUCT_SIZE_INIT() call in your
function so that we can still do it all POST_GDB.

Dave