From: Andreas Reichel <[email protected]> * Update UPDATE.md * Add new FAILSAFE.md to explain fail-safe mode
Signed-off-by: Andreas Reichel <[email protected]> --- docs/FAILSAFE.md | 10 ++++++++++ docs/UPDATE.md | 6 +++--- 2 files changed, 13 insertions(+), 3 deletions(-) create mode 100644 docs/FAILSAFE.md diff --git a/docs/FAILSAFE.md b/docs/FAILSAFE.md new file mode 100644 index 0000000..d3d0a66 --- /dev/null +++ b/docs/FAILSAFE.md @@ -0,0 +1,10 @@ +# Fail-Safe Mode # + +If more than the expected number of environments is detected during boot, the +system stops booting. This can be a problem if the user wants to boot the +system with a memory stick to update a broken installation. + +In order to allow external boot devices with other environment configurations, +the FAILSAFE flag was introduced. If any environment on the boot device has the +ENV_STATUS_FAILSAVE bit set in the `status_flags`, the boot loader will filter +out all found environments which are NOT on the boot device. diff --git a/docs/UPDATE.md b/docs/UPDATE.md index 19c2f39..9f00fd7 100644 --- a/docs/UPDATE.md +++ b/docs/UPDATE.md @@ -11,7 +11,7 @@ The structure of the environment data is as follows: struct _BG_ENVDATA { uint16_t kernelfile[ENV_STRING_LENGTH]; uint16_t kernelparams[ENV_STRING_LENGTH]; - uint8_t padding; + uint8_t status_flags; uint8_t ustate; uint16_t watchdog_timeout_sec; uint32_t revision; @@ -23,8 +23,8 @@ struct _BG_ENVDATA { The fields have the following meaning: * `kernelfile`: Path to the kernel image, utf-16 encoded * `kernelparams`: Arguments to the kernel, utf-16 encoded -* `padding`: Padding byte to stay compatible with the offsets of the previous - version. +* `status_flags`: Register to store special environment flags. Currently only + ENV_STATUS_IN_PROGRESS and ENV_STATUS_FAILSAFE are defined. * `ustate`: Update status (`0` OK, `1` INSTALLED, `2` TESTING, `3`: FAILED) * `watchdog_timeout_sec`: Number of seconds, the watchdog times out after * `revision`: The revision number explained above -- 2.17.0 -- You received this message because you are subscribed to the Google Groups "EFI Boot Guard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/efibootguard-dev/20180525120108.31055-17-andreas.reichel.ext%40siemens.com. For more options, visit https://groups.google.com/d/optout.
