Re: [PATCH v15 1/6] efi: ARM/arm64: ignore DT memory nodes instead of removing them
From: Matt Fleming <hidden>
Date: 2016-03-18 12:26:15
Also in:
linux-arm-kernel, linux-efi, lkml
On Tue, 08 Mar, at 03:59:42PM, David Daney wrote:
From: Ard Biesheuvel <redacted> There are two problems with the UEFI stub DT memory node removal routine: - it deletes nodes as it traverses the tree, which happens to work but is not supported, as deletion invalidates the node iterator; - deleting memory nodes entirely may discard annotations in the form of additional properties on the nodes. Since the discovery of DT memory nodes occurs strictly before the UEFI init sequence, we can simply clear the memblock memory table before parsing the UEFI memory map. This way, it is no longer necessary to remove the nodes, so we can remove that logic from the stub as well. Signed-off-by: Ard Biesheuvel <redacted> Signed-off-by: David Daney <david.daney-YGCgFSpz5w/QT0dZR+AlfA@public.gmane.org> --- drivers/firmware/efi/arm-init.c | 8 ++++++++ drivers/firmware/efi/libstub/fdt.c | 24 +----------------------- 2 files changed, 9 insertions(+), 23 deletions(-)
I've not delved into the rest of the series too deeply, but this looks like a straight forward change. Reviewed-by: Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>
quoted hunk ↗ jump to hunk
diff --git a/drivers/firmware/efi/arm-init.c b/drivers/firmware/efi/arm-init.c index 9e15d57..40c9d85 100644 --- a/drivers/firmware/efi/arm-init.c +++ b/drivers/firmware/efi/arm-init.c@@ -143,6 +143,14 @@ static __init void reserve_regions(void) if (efi_enabled(EFI_DBG)) pr_info("Processing EFI memory map:\n"); + /* + * Discard memblocks discovered so far: if there are any at this + * point, they originate from memory nodes in the DT, and UEFI + * uses its own memory map instead. + */ + memblock_dump_all(); + memblock_remove(0, ULLONG_MAX); + for_each_efi_memory_desc(&memmap, md) { paddr = md->phys_addr; npages = md->num_pages;
Out of curiosity, could some kind person explain (or point me at a previous explanation for) why we may have both DT memory nodes and a UEFI memory map and why they're not compatible enough to co-exist?