Re: [Crash-utility] [PATCH] Crash-Utility: s390x: Auto-detect the correct MAX_PHYSMEM_BITS used in vmcore being analyzed.
----- Original Message -----
----- 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.
And complicating matters even further, your patch presumes that the
kernel has configured CONFIG_SPARSEMEM_EXTREME in conjunction with
CONFIG_SPARSEMEM. Would it be possible for an s390x to be configured
with just CONFIG_SPARSEMEM alone? If so, your patch breaks down.
Or is there another way you can determine which MAX_PHYSMEM_BITS value
is in use?
Dave