mirror of
https://github.com/AsahiLinux/u-boot
synced 2024-11-05 20:54:31 +00:00
fae81c72c8
Update documentation according to the EXT SPL support patch set. Signed-off-by: Guillaume GARDET <guillaume.gardet@free.fr> Cc: Tom Rini <trini@ti.com>
97 lines
3.3 KiB
Text
97 lines
3.3 KiB
Text
Generic SPL 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
|
|
has been created. With this framework almost all source files for a board
|
|
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.
|
|
|
|
A config option named CONFIG_SPL_BUILD is enabled by Kconfig for SPL.
|
|
Source files can therefore be compiled for SPL with different settings.
|
|
|
|
For example:
|
|
|
|
ifeq ($(CONFIG_SPL_BUILD),y)
|
|
obj-y += board_spl.o
|
|
else
|
|
obj-y += board.o
|
|
endif
|
|
|
|
obj-$(CONFIG_SPL_BUILD) += foo.o
|
|
|
|
#ifdef CONFIG_SPL_BUILD
|
|
foo();
|
|
#endif
|
|
|
|
|
|
The building of SPL images can be enabled by CONFIG_SPL option 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.
|
|
|
|
To support generic U-Boot libraries and drivers in the SPL binary one can
|
|
optionally define CONFIG_SPL_XXX_SUPPORT. Currently following options
|
|
are supported:
|
|
|
|
CONFIG_SPL_LIBCOMMON_SUPPORT (common/libcommon.o)
|
|
CONFIG_SPL_LIBDISK_SUPPORT (disk/libdisk.o)
|
|
CONFIG_SPL_I2C_SUPPORT (drivers/i2c/libi2c.o)
|
|
CONFIG_SPL_GPIO_SUPPORT (drivers/gpio/libgpio.o)
|
|
CONFIG_SPL_MMC_SUPPORT (drivers/mmc/libmmc.o)
|
|
CONFIG_SPL_SERIAL_SUPPORT (drivers/serial/libserial.o)
|
|
CONFIG_SPL_SPI_FLASH_SUPPORT (drivers/mtd/spi/libspi_flash.o)
|
|
CONFIG_SPL_SPI_SUPPORT (drivers/spi/libspi.o)
|
|
CONFIG_SPL_FAT_SUPPORT (fs/fat/libfat.o)
|
|
CONFIG_SPL_EXT_SUPPORT
|
|
CONFIG_SPL_LIBGENERIC_SUPPORT (lib/libgeneric.o)
|
|
CONFIG_SPL_POWER_SUPPORT (drivers/power/libpower.o)
|
|
CONFIG_SPL_NAND_SUPPORT (drivers/mtd/nand/libnand.o)
|
|
CONFIG_SPL_DRIVERS_MISC_SUPPORT (drivers/misc)
|
|
CONFIG_SPL_DMA_SUPPORT (drivers/dma/libdma.o)
|
|
CONFIG_SPL_POST_MEM_SUPPORT (post/drivers/memory.o)
|
|
CONFIG_SPL_NAND_LOAD (drivers/mtd/nand/nand_spl_load.o)
|
|
CONFIG_SPL_SPI_LOAD (drivers/mtd/spi/spi_spl_load.o)
|
|
CONFIG_SPL_RAM_DEVICE (common/spl/spl.c)
|
|
CONFIG_SPL_WATCHDOG_SUPPORT (drivers/watchdog/libwatchdog.o)
|
|
|
|
|
|
Debugging
|
|
---------
|
|
|
|
When building SPL with DEBUG set you may also need to set CONFIG_PANIC_HANG
|
|
as in most cases do_reset is not defined within SPL.
|
|
|
|
|
|
Estimating stack usage
|
|
----------------------
|
|
|
|
With gcc 4.6 (and later) and the use of GNU cflow it is possible to estimate
|
|
stack usage at various points in run sequence of SPL. The -fstack-usage option
|
|
to gcc will produce '.su' files (such as arch/arm/cpu/armv7/syslib.su) that
|
|
will give stack usage information and cflow can construct program flow.
|
|
|
|
Must have gcc 4.6 or later, which supports -fstack-usage
|
|
|
|
1) Build normally
|
|
2) Perform the following shell command to generate a list of C files used in
|
|
SPL:
|
|
$ find spl -name '*.su' | sed -e 's:^spl/::' -e 's:[.]su$:.c:' > used-spl.list
|
|
3) Execute cflow:
|
|
$ cflow --main=board_init_r `cat used-spl.list` 2>&1 | $PAGER
|
|
|
|
cflow will spit out a number of warnings as it does not parse
|
|
the config files and picks functions based on #ifdef. Parsing the '.i'
|
|
files instead introduces another set of headaches. These warnings are
|
|
not usually important to understanding the flow, however.
|