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| author | Heinrich Schuchardt <heinrich.schuchardt@canonical.com> | 2023-07-28 19:44:34 +0300 |
|---|---|---|
| committer | Heinrich Schuchardt <heinrich.schuchardt@canonical.com> | 2023-08-03 10:21:02 +0300 |
| commit | f945327adf24bafde599a68c93d4f0ad3ee80160 (patch) | |
| tree | cb040ae8d7b50de557abd6445bdcf3b8c7b9ed16 /doc | |
| parent | 38dedebc547f795efc3daad17f7c013c515e1285 (diff) | |
| download | u-boot-f945327adf24bafde599a68c93d4f0ad3ee80160.tar.xz | |
doc: U-Boot boot phases
Add more detail to the description of U-Boot boot phases:
* describe which steps are optional
* mentions alternative boot flows
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/develop/spl.rst | 13 |
1 files changed, 10 insertions, 3 deletions
diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst index a1515a7b43..76e87f07c7 100644 --- a/doc/develop/spl.rst +++ b/doc/develop/spl.rst @@ -77,10 +77,11 @@ To check whether a feature is enabled, use CONFIG_IS_ENABLED():: This checks CONFIG_CLK for the main build, CONFIG_SPL_CLK for the SPL build, CONFIG_TPL_CLK for the TPL build, etc. -U-Boot Phases -------------- +U-Boot Boot Phases +------------------ -U-Boot boots through the following phases: +U-Boot goes through the following boot phases where TPL, VPL, SPL are optional. +While many boards use SPL, less use TPL. TPL Very early init, as tiny as possible. This loads SPL (or VPL if enabled). @@ -97,6 +98,12 @@ SPL U-Boot U-Boot proper, containing the command line and boot logic. +Further usages of U-Boot SPL comprise: + +* Launching BL31 of ARM Trusted Firmware which invokes main U-Boot as BL33 +* launching EDK II +* launching Linux kernel +* launching RISC-V OpenSBI which invokes main U-Boot Checking the boot phase ----------------------- |