Hi Marek, On Wed, 27 Oct 2021 at 21:28, Marek Behún <ka...@kernel.org> wrote: > > From: Marek Behún <marek.be...@nic.cz> > > Hello Simon, Stefan, Pali, > > this series adds support for board specific runtime determined
grammarian here board-specific, runtime-determined > default environment variables. > > IMPORTANT: This series depends on the series > http://patchwork.ozlabs.org/project/uboot/list/?series=268452 > > Currently the > env default [-a] > command uses the default_environment[] buffer to get the default > env variables. > > Sometimes it makes sense to have runtime determined default env > settings. > > For example the ESPRESSObin board has 4 variants > ([ddr3 vs ddr4] x [emmc vs sd]), and each uses different device tree. > Thus the `fdtfile` env variable has different values for these 4 > variants. (We can't set this variable via env_set() in some board init > function, because then the user would be unable to overwrite it.) > In order for the command > env default fdtfile > to work as the user would expect, we need to support overwriting default > environment in runtime. > > Pali solved this for ESPRESSObin by declaring the default_environment[] > buffer read-write, instead of read-only, and adding ad-hoc code into > board_late_init() that writes into the default_environment[] buffer. > > This ad-hoc code works, but it would be better to have a generic API > for this, since there are other boards which could benefit. > > The first 3 patches in this series fix and simplify code in > env/common.c. > > The 4th patch adds support for board specific runtime determined > default environment in such a way that if a board code defines function > > const char *board_special_default_env(unsigned i, const char **name); > > The default weak implementation of this function is trivial and just > returns NULL. > This function is to be defined in board code, and when defined, it must > return the value of the i-th runtime determined default env variable, > while storing its name into *name. > > For example: > const char *board_special_default_env(unsigned i, const char **name) > { > switch (i) { > case 0: > *name = "board"; > return is_ddr4() ? "my_board_ddr4" : "my_board"; > case 1: > *name = "fdtfile"; > return is_ddr4() ? "my-board-ddr4.dtb" : "my-board.dtb"; > default: > return NULL; > } > > The last patch (NOT TESTED) converts the ESPRESSObin ad-hoc code to > use this API. > > Marek > > Marek Behún (5): > env: Don't set ready flag if import failed in env_set_default() > env: Fix env_get() when returning empty string using env_get_f() > env: Simplify env_get_default() > env: Add support for board specific special default environment > arm: mvebu: Espressobin: Use new API for setting default env at > runtime > > board/Marvell/mvebu_armada-37xx/board.c | 120 ++++++++++------ > configs/mvebu_espressobin-88f3720_defconfig | 1 - > env/common.c | 150 ++++++++++++++++---- > include/configs/mvebu_armada-37xx.h | 17 +-- > include/env_default.h | 2 - > include/env_internal.h | 4 - > 6 files changed, 199 insertions(+), 95 deletions(-) > > -- > 2.32.0 > Regards, Simon
