diff options
| author | Rob Clark <robdclark@gmail.com> | 2017-09-13 18:05:37 -0400 |
|---|---|---|
| committer | Alexander Graf <agraf@suse.de> | 2017-09-20 11:00:57 +0200 |
| commit | ad644e7c18238026fecc647f62584d87d2c5b0a3 (patch) | |
| tree | e46e831f196cc6f2df00cf501e39eecea5f2bb4c /cmd | |
| parent | 946160f334ddaf2dd0dfd4bc72485f9ce39dc2cd (diff) | |
efi_loader: efi variable support
Add EFI variable support, mapping to u-boot environment variables.
Variables are pretty important for setting up boot order, among other
things. If the board supports saveenv, then it will be called in
ExitBootServices() to persist variables set by the efi payload. (For
example, fallback.efi configuring BootOrder and BootXXXX load-option
variables.)
Variables are *not* currently exposed at runtime, post ExitBootServices.
On boards without a dedicated device for storage, which the loaded OS
is not trying to also use, this is rather tricky. One idea, at least
for boards that can persist RAM across reboot, is to keep a "journal"
of modified variables in RAM, and then turn halt into a reboot into
u-boot, plus store variables, plus halt. Whatever the solution, it
likely involves some per-board support.
Mapping between EFI variables and u-boot variables:
efi_$guid_$varname = {attributes}(type)value
For example:
efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported=
"{ro,boot,run}(blob)0000000000000000"
efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_BootOrder=
"(blob)00010000"
The attributes are a comma separated list of these possible
attributes:
+ ro - read-only
+ boot - boot-services access
+ run - runtime access
NOTE: with current implementation, no variables are available after
ExitBootServices, and all are persisted (if possible).
If not specified, the attributes default to "{boot}".
The required type is one of:
+ utf8 - raw utf8 string
+ blob - arbitrary length hex string
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Alexander Graf <agraf@suse.de>
Diffstat (limited to 'cmd')
| -rw-r--r-- | cmd/bootefi.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/cmd/bootefi.c b/cmd/bootefi.c index c1ef1b542b..9f844737e5 100644 --- a/cmd/bootefi.c +++ b/cmd/bootefi.c @@ -181,6 +181,10 @@ static unsigned long do_bootefi_exec(void *efi, void *fdt, goto exit; } + /* we don't support much: */ + env_set("efi_8be4df61-93ca-11d2-aa0d-00e098032b8c_OsIndicationsSupported", + "{ro,boot}(blob)0000000000000000"); + /* Call our payload! */ debug("%s:%d Jumping to 0x%lx\n", __func__, __LINE__, (long)entry); |