[RFC PATCH 0/3] Remove unused EFI runtime APIs

[Ard Biesheuvel <ardb+git@xxxxxxxxxx>]

From: Ard Biesheuvel <ardb@xxxxxxxxxx>

Using EFI runtime services to program the RTC to wake up the system is
supported in theory, but rarely works in practice. Fortunately, this
functionality is rarely [if ever] used to begin with so we can just drop
it. (Note that the EFI rtc driver is not used by x86, which programs the
CMOS rtc directly)

The same applies to GetNextHighMonoCount(), which, if implemented,
usually relies on SetVariable() under the hood *, which is often not
supported at runtime by non-x86 platforms. But it has no known users
either so let's drop support for it as well.

This means we need to drop the slightly pointless tests for it too.

* EDK2 based EFI implementations usually have a MTC variable carrying
  the monotonic counter variable, which is therefore not truly
  monotonic, given that SetVariable() will happily overwrite it. 

Cc: Heinrich Schuchardt <heinrich.schuchardt@xxxxxxxxxxxxx>
Cc: Feng Tang <feng.tang@xxxxxxxxxxxxxxxxx>
Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> 
Cc: Sunil V L <sunilvl@xxxxxxxxxxxxxxxx>
Cc: Bibo Mao <maobibo@xxxxxxxxxxx>
Cc: linux-rtc@xxxxxxxxxxxxxxx
Cc: linux-efi@xxxxxxxxxxxxxxx
Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
Cc: linux-riscv@xxxxxxxxxxxxxxxxxxx
Cc: loongarch@xxxxxxxxxxxxxxx

Ard Biesheuvel (3):
  efi-rtc: Remove wakeup functionality
  efi/test: Don't bother pseudo-testing unused EFI services
  efi: Remove support for pointless, unused EFI services

 arch/x86/platform/efi/efi_64.c          |  22 ----
 drivers/firmware/efi/runtime-wrappers.c |  68 ------------
 drivers/firmware/efi/test/efi_test.c    | 108 +-------------------
 drivers/rtc/rtc-efi.c                   |  76 +-------------
 drivers/xen/efi.c                       |  56 ----------
 include/linux/efi.h                     |   6 --
 6 files changed, 4 insertions(+), 332 deletions(-)

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2.50.0.727.gbf7dc18ff4-goog