Hi Simon, On Thu, 6 Dec 2018 at 03:31, Simon Glass <[email protected]> wrote: > > Hi, > > On Tue, 27 Nov 2018 at 12:57, Ruslan Trofymenko > <[email protected]> wrote: > > > > Add a short documentation for A/B enablement and 'android_ab_select' > > command usage. > > > > Signed-off-by: Ruslan Trofymenko <[email protected]> > > --- > > doc/README.android-ab | 67 > > +++++++++++++++++++++++++++++++++++++++++++++++++++ > > 1 file changed, 67 insertions(+) > > create mode 100644 doc/README.android-ab > > > > diff --git a/doc/README.android-ab b/doc/README.android-ab > > new file mode 100644 > > index 0000000..230088c > > --- /dev/null > > +++ b/doc/README.android-ab > > @@ -0,0 +1,67 @@ > > +Android A/B updates > > +=================== > > + > > +Overview > > +-------- > > + > > +A/B system updates ensures modern approach for system update. This feature > > +allows one to use two sets (or more) of partitions referred to as slots > > +(normally slot A and slot B). The system runs from the current slot while > > the > > +partitions in the unused slot can be updated [1]. > > + > > +A/B enablement > > +-------------- > > + > > +The A/B updates support can be activated by specifying next options in > > +your board configuration file: > > + > > + CONFIG_ANDROID_AB=y > > + CONFIG_CMD_ANDROID_AB_SELECT=y > > + > > +The disk space on target device must be partitioned in a way so that each > > +partition which needs to be updated has two or more instances. The name of > > +each instance must be formed by adding suffixes: _a, _b, _c, etc. > > +For example: boot_a, boot_b, system_a, system_b, vendor_a, vendor_b. > > + > > +As a result you can use 'android_ab_select' command to ensure A/B boot > > process > > +in your boot script. This command analyzes and processes A/B metadata > > stored > > +on a special partition (e.g. "misc") and determines which slot should be > > used > > +for booting up. > > + > > +Command usage > > +------------- > > + > > + android_ab_select <slot_var_name> <interface> > > <dev[:part_number|#part_name]> > > Can we have a shorter command? > > Perhaps we need a new 'android' command with an 'ab_select' > subcommand? Then the automatica abbreviation will work. >
Agree with all your previous comments, will send v2 shortly. But this one I'd like to leave as is (I will drop android_ prefix though). I think adding "android" command may lead to unneeded architecture complexity in future, e.g.: - we will need to re-work next commands as sub-commands of "android" command: fastboot, dtimg, mmc_swrite (which can be hard as ab_select command file has BSD license and other commands have GPL license) - we will need to implement sub-sub-commands (e.g. for "android dtimg dump ..." etc.) - having "android" command can be inconvenient for users and may break existing API (e.g. it will force users to use "android fastboot" instead of just "fastboot" command) - actually I don't see any namespace issues that can be solved by adding "android" command Also, in subsequent patch, I will add the dedicated menu option for Android-related commands and will pull all existing Android commands (along with ab_select) to that menu entry. So I hope it's fine with you if I leave this command as "ab_select"? Thanks. > > + > > +for example: > > + > > + => android_ab_select slot_name mmc 1:4 > > + > > +or > > + > > + => android_ab_select slot_name mmc 1#misc > > + > > +Result: > > + > > + => printenv slot_name > > + slot_name=a > > + > > +Based on this slot information, the current boot partition should be > > defined, > > +and next kernel command line parameters should be generated: > > + > > + - androidboot.slot_suffix= > > + - root= > > + > > +For example: > > + > > + androidboot.slot_suffix=_a root=/dev/mmcblk1p12 > > + > > +A/B metadata is organized according to AOSP reference [2]. On the first > > system > > +start with A/B enabled, when 'misc' partition doesn't contain required > > data, > > +the default A/B metadata will be created and written to 'misc' partition. > > + > > +References > > +---------- > > + > > +[1] https://source.android.com/devices/tech/ota/ab > > +[2] > > bootable/recovery/bootloader_message/include/bootloader_message/bootloader_message.h > > -- > > 2.7.4 > > > > Regards, > Simon _______________________________________________ U-Boot mailing list [email protected] https://lists.denx.de/listinfo/u-boot
