[U-Boot] [PATCH v2 00/11] efi_loader: non-volatile variables support

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

This patch set is an attempt to implement non-volatile attribute for
UEFI variables. Under the current implementation,
* SetVariable API doesn't recognize non-volatile attribute
* While some variables are defined non-volatile in UEFI specification,
  they are NOT marked as non-volatile in the code.
* env_save() (or "env save" command) allows us to save all the variables
  into persistent storage, but it may cause volatile UEFI variables,
  along with irrelevant U-Boot variables, to be saved unconditionally.

Those observation rationalizes that the implementation of UEFI variables
should be revamped utilizing dedicated storage for them.

This patch set is yet experimental and rough-edged(See known issues below),
but shows how UEFI variables can be split from U-Boot environment.
This enhancement will also be vital when we introduce UEFI secure boot
where secure and tamper-resistant storage (with authentication) is
required.

Usage:
To enable this feature, the following configs must be enabled:
  CONFIG_ENV_IS_IN_FAT
  CONFIG_ENV_FAT_INTERFACE
  CONFIG_ENV_EFI_FAT_DEVICE_AND_PART
  CONFIG_ENV_EFI_FAT_FILE

You can also define a non-volatile variable from command interface:
=> setenv -e -nv FOO baa

Known issues/restriction:
* UEFI spec defines "globally defined variables" with specific
  attributes, but with this patch, we don't check against the user-supplied
  attribute for any variable.
* Only FAT can be enabled for persistent storage for UEFI non-volatile
  variables.
* The whole area of storage will be saved at every update of one variable.
  It can be optimized.
* An error during saving may cause inconsistency between cache (hash table)
  and the storage.
* Cache is of fixed size and can be quite big for normal usage.

Patch#1 to #4 are preparatory so that we won't rely on U-Boot environment,
that is, env_get/set() helper functions.
Patch#5 to #8 are core part of changes.
Patch#9 to #11 are for modifying variable attributes.

Changes in v2 (Apr 24, 2019)
* rebased on efi-2019-07
* revamp the implementation

v1 (Nov 28, 2018)
* initial

AKASHI Takahiro (11):
  lib: charset: add u16_strcmp()
  lib: charset: add u16_strncmp()
  cmd: efidebug: rework "boot dump" sub-command using
    GetNextVariableName()
  efi_loader: set OsIndicationsSupported at init
  env: save UEFI non-volatile variables in dedicated storage
  efi_loader: variable: support non-volatile attribute
  efi_loader: variable: split UEFI variables from U-Boot environment
  efi_loader: load saved non-volatile variables at init
  efi_loader: bootmgr: handle BootNext as non-volatile
  cmd: env: add -nv option for UEFI non-volatile variable
  cmd: efidebug: make some boot variables non-volatile

 cmd/bootefi.c                     |   4 -
 cmd/efidebug.c                    |  95 +++++++++++-----
 cmd/nvedit.c                      |   3 +-
 cmd/nvedit_efi.c                  |  15 ++-
 env/Kconfig                       |  34 ++++++
 env/env.c                         |  98 ++++++++++++++++-
 env/fat.c                         | 109 +++++++++++++++++++
 include/asm-generic/global_data.h |   1 +
 include/charset.h                 |  10 ++
 include/environment.h             |  24 +++++
 lib/charset.c                     |  23 ++++
 lib/efi_loader/efi_bootmgr.c      |   3 +-
 lib/efi_loader/efi_setup.c        |  13 +++
 lib/efi_loader/efi_variable.c     | 174 ++++++++++++++++++++++++++++--
 14 files changed, 560 insertions(+), 46 deletions(-)

-- 
2.20.1