A large chunk of the U-Boot code is its wide variety of commands. For some applications this is not needed, since the boot can be controlled by a board-specific hard-coded boot procedure.
Any attempt to use commands, such as running script, will result in an error. U-Boot acts as if it supports commands in general, but there are no actual commands to run.
This saves a significant amount of space.
For example on snow this saves 300KB of code space, with the code size dropping from 505KB to 202KB. BSS drops from 238KB to 4KB. The size of u-boot.bin (which includes the device tree) drops from 541KB to 228KB.
If LCD and USB support is disabled on this platform, code size drops to 139KB.
This makes U-Boot proper look a little more like SPL in terms of size.
The CONFIG_CMDLINE setting is enabled by default, but can be disabled by boards as needed.
Simon Glass (9): cbfs: Update a function to be static Add an option to enable the command line arm: x86: Drop command-line code when CONFIG_CMDLINE is disabled sandbox: Avoid calling commands when not available Drop command-processing code when CONFIG_CMDLINE is disabled Hang when no command line processing can be performed Allow command code to compile to nothing Allow command-line files to be dropped Drop various features when the command line is not available
README | 8 ++++++++ arch/arm/cpu/u-boot.lds | 3 +++ arch/sandbox/cpu/start.c | 10 +++++++++- arch/x86/cpu/u-boot.lds | 4 ++++ cmd/Kconfig | 12 ++++++++++++ cmd/cbfs.c | 12 ++++++++---- cmd/help.c | 4 ++++ common/Makefile | 4 ++-- common/cli.c | 17 +++++++++++++++- common/command.c | 6 ++++++ common/main.c | 1 + include/command.h | 49 ++++++++++++++++++++++++++++++++++++++++++---- include/config_fallbacks.h | 10 ++++++++++ 13 files changed, 128 insertions(+), 12 deletions(-)