Update the various references to SPL in this document. Make sure to refer to 'phases' instead of 'stages', which is not a U-Boot term.
Fix a few U-boot typos and try to improve grammar a little while we are here.
Signed-off-by: Simon Glass sjg@chromium.org ---
(no changes since v2)
Changes in v2: - Move to earlier in the series
doc/develop/spl.rst | 79 +++++++++++++++++++++++---------------------- 1 file changed, 41 insertions(+), 38 deletions(-)
diff --git a/doc/develop/spl.rst b/doc/develop/spl.rst index a92110e4fa9..aa6d28fa333 100644 --- a/doc/develop/spl.rst +++ b/doc/develop/spl.rst @@ -1,11 +1,12 @@ -Generic SPL framework +Generic xPL framework =====================
Overview --------
-To unify all existing implementations for a secondary program loader (SPL) -and to allow simply adding of new implementations this generic SPL framework +To unify all existing implementations for secondary/tertiary program loaders +(generically called xPL) +and to allow simply adding of new implementations this generic xPL framework has been created. With this framework almost all source files for a board can be reused. No code duplication or symlinking is necessary anymore.
@@ -13,38 +14,39 @@ can be reused. No code duplication or symlinking is necessary anymore. How it works ------------
-The object files for SPL are built separately and placed in the "spl" directory. -The final binaries which are generated are u-boot-spl, u-boot-spl.bin and -u-boot-spl.map. +The object files for xPL are built separately and placed in a subdirectory +("spl", "tpl" or "vpl"). +The final binaries which are generated for SPL are u-boot-spl, u-boot-spl.bin +and u-boot-spl.map
-A config option named CONFIG_SPL_BUILD is enabled by Kconfig for SPL. -Source files can therefore be compiled for SPL with different settings. +A config option named CONFIG_XPL_BUILD is enabled by Kconfig for xPL builds. +Source files can therefore be compiled for xPL with different settings.
For example::
- ifeq ($(CONFIG_SPL_BUILD),y) + ifeq ($(CONFIG_XPL_BUILD),y) obj-y += board_spl.o else obj-y += board.o endif
- obj-$(CONFIG_SPL_BUILD) += foo.o + obj-$(CONFIG_XPL_BUILD) += foo.o
- #ifdef CONFIG_SPL_BUILD + if (IS_ENABLED(CONFIG_XPL_BUILD)) foo(); - #endif
if (xpl_phase() == PHASE_TPL) bar();
-The building of SPL images can be enabled by CONFIG_SPL option in Kconfig. +The building of xPL images can be enabled by CONFIG_SPL (etc.) options in +Kconfig.
-Because SPL images normally have a different text base, one has to be -configured by defining CONFIG_SPL_TEXT_BASE. The linker script has to be -defined with CONFIG_SPL_LDSCRIPT. +Because xPL images normally have a different text base, one has to be +configured by defining CONFIG_xPL_TEXT_BASE. The linker script has to be +defined with CONFIG_xPL_LDSCRIPT.
-To support generic U-Boot libraries and drivers in the SPL binary one can -optionally define CONFIG_SPL_XXX_SUPPORT. Currently following options +To support generic U-Boot libraries and drivers in the xPL binary one can +optionally define CONFIG_xPL_XXX_SUPPORT. Currently following options are supported:
CONFIG_SPL_LIBCOMMON_SUPPORT (common/libcommon.o) @@ -77,7 +79,7 @@ CONFIG_SPL_DM_GPIO (drivers/gpio/gpio-uclass.o) CONFIG_SPL_BMP (drivers/video/bmp.o) CONFIG_SPL_BLOBLIST (common/bloblist.o)
-Adding SPL-specific code +Adding xPL-specific code ------------------------
To check whether a feature is enabled, use CONFIG_IS_ENABLED():: @@ -92,7 +94,7 @@ U-Boot Boot Phases ------------------
U-Boot goes through the following boot phases where TPL, VPL, SPL are optional. -While many boards use SPL, less use TPL. +While many boards use SPL, fewer use TPL.
TPL Very early init, as tiny as possible. This loads SPL (or VPL if enabled). @@ -179,29 +181,30 @@ files instead introduces another set of headaches. These warnings are not usually important to understanding the flow, however.
-Reserving memory in SPL +Reserving memory in xPL -----------------------
-If memory needs to be reserved in RAM during SPL stage with the requirement that -the SPL reserved memory remains preserved across further boot stages too +If memory needs to be reserved in RAM during an xPL phase with the requirement +that the xPL reserved memory remains preserved across further boot phases too then it needs to be reserved mandatorily starting from end of RAM. This is to -ensure that further stages can simply skip this region before carrying out +ensure that further phases can simply skip this region before carrying out further reservations or updating the relocation address.
-Also out of these regions which are to be preserved across further stages of +Also out of these regions which are to be preserved across further phases of boot, video framebuffer memory region must be reserved first starting from -end of RAM for which helper function spl_reserve_video_from_ram_top is provided -which makes sure that video memory is placed at top of reservation area with +end of RAM for which the helper function spl_reserve_video_from_ram_top() is +provided +which makes sure that video memory is placed at the top of reservation area with further reservations below it.
-The corresponding information of reservation for those regions can be passed to -further boot stages using a bloblist. For e.g. the information for -framebuffer area reserved by SPL can be passed onto U-boot using -BLOBLISTT_U_BOOT_VIDEO. - -The further boot stages need to parse each of the bloblist passed from SPL stage -starting from video bloblist and skip this whole SPL reserved memory area from -end of RAM as per the bloblists received, before carrying out further -reservations or updating the relocation address. For e.g, U-boot proper uses -function "setup_relocaddr_from_bloblist" to parse the bloblists passed from -previous stage and skip the memory reserved from previous stage accordingly. +The reservation information for these regions can be passed to the +further boot phases using a bloblist. For e.g. the information for the +framebuffer area reserved by xPL can be passed onto U-Boot using +BLOBLISTT_U_BOOT_VIDEO + +The further boot phases need to parse each of the blobs passed from xPL phase +starting from video bloblist and skip this whole xPL reserved-memory area from +end of RAM as per the blobs received, before carrying out further +reservations or updating the relocation address. For e.g, U-Boot proper uses +function setup_relocaddr_from_bloblist() to parse the bloblist passed from +previous phase and skip the memory reserved from previous phase accordingly.