On 8/27/21 9:55 AM, Kristian Amlie wrote:

You can use scripts/get_maintainer.pl to find the right addressees for your patches.

efi_reserve_memory() states that memory marked with "no-map" shall not be accessed by the UEFI payload. Make sure efi_get_memory_map() honors this.

This helps the case when booting vexpress_ca9x4 under QEMU. Because the kernel wants to use an address in the lowest 128MiB of the range, but this range is reserved with "no-map", the kernel complains that it can not allocate the low memory it needs. In reality the actual usable memory starts much higher, which is reflected correctly in the memory map after this fix.

The 'no-map' requirement needs to be fulfilled by the kernel.

The GetMemoryMap() boot time service must comply to the UEFI specification.

The Devicetree Specification has this clarification:

"Reserved regions with the no-map property must be listed in the memory map with type EfiReservedMemoryType. All other reserved regions must be listed with type EfiBootServicesData." https://devicetree-specification.readthedocs.io/en/latest/chapter3-devicenod...

Should the kernel calculate its internal 128 MiB requirement incorrectly this needs be fixed in the kernel EFI stub. Does the problem exist with kernel 5.14?

I wonder if the 128 MiB requirement of the kernel can be lifted for 32bit ARM as we already did for RISC-V. Cf.

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?h...

Cc Ard, maintainer of the kernel EFI stub.

Best regards

Heinrich

Signed-off-by: Kristian Amlie kristian.amlie@northern.tech

lib/efi_loader/efi_memory.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c index f4acbee4f9..7f8543143a 100644 --- a/lib/efi_loader/efi_memory.c +++ b/lib/efi_loader/efi_memory.c @@ -646,8 +646,16 @@ efi_status_t efi_get_memory_map(efi_uintn_t *memory_map_size,

provided_map_size = *memory_map_size;

• list_for_each(lhandle, &efi_mem)

• list_for_each(lhandle, &efi_mem) {

• struct efi_mem_list *lmem;
  

• lmem = list_entry(lhandle, struct efi_mem_list, link);
  

• if (lmem->desc.type == EFI_RESERVED_MEMORY_TYPE)
  

• 	continue;
  

• map_entries++;

• }

  map_size = map_entries * sizeof(struct efi_mem_desc);

@@ -672,6 +680,10 @@ efi_status_t efi_get_memory_map(efi_uintn_t *memory_map_size, struct efi_mem_list *lmem;

lmem = list_entry(lhandle, struct efi_mem_list, link);

• if (lmem->desc.type == EFI_RESERVED_MEMORY_TYPE)
  

• 	continue;
  

• *memory_map = lmem->desc; memory_map--; }