Re: [PATCH v4 0/6] arm64 UEFI early FDT handling

[Robert Richter]

(+RobH and MarkR)

On 09.02.16 15:35:42, Ard Biesheuvel wrote:
> (+ Grant)
> 
> On 9 February 2016 at 14:53, Robert Richter <rrichter@xxxxxxxxxxxxxxxxxx> wrote:
> > From: Robert Richter <rrichter@xxxxxxxxxx>
> >
> > Reposting an updated version of this patches ported to 4.5-rc1. It is
> > a followup to the version 3 from:
> >
> >  http://lkml.kernel.org/r/1442881288-13962-1-git-send-email-ard.biesheuvel@xxxxxxxxxx
> >
> > The series is essential for NUMA on arm64. Early FDT handling is
> > required to make system topology data from firmware, esp. for cpus and
> > memory available to the early boot process. Ganapat's numa patches
> > depend on it. This series has been tested with his series v10 posted
> > here:
> >
> >  http://lkml.kernel.org/r/1454407763-1017-1-git-send-email-gkulkarni@xxxxxxxxxxxxxxxxxx
> >
> 
> Hello Robert,
> 
> This series does not reflect anymore what we think is the best way to
> deal with memory nodes and memreserves on UEFI systems.
> Please refer to this thread:
> http://thread.gmane.org/gmane.linux.kernel.efi/6464
> 
> As far as the memory nodes are concerned, if it is the best place to
> store these NUMA annotations, then we should indeed preserve them, but
> I think the discussion stalled without any conclusion having been
> reached. As far as the /reserved-memory node is concerned, that one we
> should really keep, so at least patch 6/6 of this series should be
> replaced with something based on the series above.

Ard,

Mark R and Rob have agreed for numa dt binding for mem nodes. So do
you think we can at least reuse parts of this series to solve the NUMA
issue and try to find a solution for patch #6 which aligns with your
alternative approach?

Thanks,

-Robert

> 
> Thanks,
> Ard.
> 
> 
> > A number of minor issues exist in the early UEFI/FDT handling path, such as:
> > - when booting via UEFI, memreserve entries are removed from the device tree but
> >   the /reserved-memory node is not
> > - memory nodes are removed from the device tree in a way that is not officially
> >   supported by the libfdt API (i.e., you cannot delete nodes while traversing
> >   the tree)
> > - removal of memory nodes may discard annotations (such as NUMA topology) that
> >   should ideally be retained, or may corrupt the tree by discarding nodes
> >   referenced by phandles.
> >
> > Patches #1 and #2 introduce an arm64 specific version of
> > early_init_dt_add_memory_arch() so that we can modify it later to ignore DT
> > memory nodes if booting via UEFI.
> >
> > Patch #3 moves some UEFI+FDT init code around before making changes to it.
> >
> > Patch #4 moves the UEFI initialization to before the early FDT scanning so we
> > know at that point whether we are booting via UEFI or not.
> >
> > Patch #5 changes the UEFI init code so that memory nodes are simply ignored, so
> > that they don't have to be removed by the stub anymore.
> >
> > Patch #6 does the same as #5, but for memreserves and the /reserved-memory
> > node.
> >
> > Changes since v3:
> > - prorted to v4.5-rc1
> >
> > Changes since v2:
> > - instead of copying the generic implementation, turn
> >   early_init_dt_add_memory_arch() into a weak alias so that it is still
> >   accessible to overrides
> >
> > Changes since v1:
> > - dropped first two patches, they have been merged into v4.2-rc1
> > - dropped last patch regarding FDT placement by the stub, this is not entirely
> >   relevant to the primary issue targeted by this series
> > - rebased onto for-next/core (arm64) as of today
> >
> > Ard Biesheuvel (6):
> >   of/fdt: make generic early_init_dt_add_memory_arch() a weak alias
> >   arm64: override generic version of early_init_dt_add_memory_arch()
> >   efi: move FDT handling to separate object file
> >   arm64/efi: move EFI /chosen node parsing before early FDT processing
> >   arm64/efi: ignore DT memory nodes instead of removing them
> >   arm64/efi: ignore DT memreserve entries instead of removing them
> >
> >  arch/arm64/include/asm/efi.h       |  2 +
> >  arch/arm64/kernel/setup.c          |  3 ++
> >  arch/arm64/mm/init.c               | 12 +++++-
> >  drivers/firmware/efi/Makefile      |  1 +
> >  drivers/firmware/efi/arm-init.c    | 36 ++++++++++------
> >  drivers/firmware/efi/efi-fdt.c     | 73 +++++++++++++++++++++++++++++++++
> >  drivers/firmware/efi/efi.c         | 84 --------------------------------------
> >  drivers/firmware/efi/libstub/fdt.c | 33 +--------------
> >  drivers/of/fdt.c                   |  7 +++-
> >  include/linux/efi.h                |  2 +-
> >  include/linux/of_fdt.h             |  1 +
> >  11 files changed, 121 insertions(+), 133 deletions(-)
> >  create mode 100644 drivers/firmware/efi/efi-fdt.c
> >
> > --
> > 2.7.0.rc3