7811a8ae52
Add an example of a program which boots an OS by calling into the U-Boot library. Series-to: concept Co-developed-by: Claude <noreply@anthropic.com> Co-developed-by: Simon Glass <sjg@chromium.org> Signed-off-by: Simon Glass <sjg@chromium.org> Series-links: 1:28
90 lines
2.4 KiB
Plaintext
90 lines
2.4 KiB
Plaintext
U-Boot Library Example
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======================
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This directory contains example programs showing how to use the U-Boot library
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(libu-boot.so) in external C programs.
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Building U-Boot Library
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-----------------------
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First, build U-Boot with library support:
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make O=/tmp/b/sandbox -j$(nproc) sandbox_defconfig all
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This creates:
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- /tmp/b/sandbox/libu-boot.so (shared library)
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- /tmp/b/sandbox/libu-boot.a (static library)
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Example Programs
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----------------
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The examples are built automatically as part of the U-Boot build. Each program
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demonstrates different aspects of the U-Boot library.
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**demo.c** - Demonstrates using U-Boot library functions
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- Shows how to init the library with ulib_init()
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- Uses U-Boot's OS functions (os_open(), os_fgets(), os_close())
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- Reads and displays system information
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- Shows the U-Boot version
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**boot.c** - Demonstrates booting an OS using U-Boot bootflow
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- Shows bootflow scanning and booting functionality
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- Uses system headers for main program logic (boot.c)
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- Uses U-Boot headers for bootflow internals (bootflow.c)
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- Demonstrates attaching disk images and scanning for bootable OS
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- Attempts to boot the first discovered bootflow
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Building Examples
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-----------------
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The examples are built automatically when U-Boot has these options enabled::
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CONFIG_ULIB=y
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CONFIG_EXAMPLES=y
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To build manually:
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# From this directory examples/ulib
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make UBOOT_BUILD=/tmp/b/sandbox/ srctree=../..
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Running Examples
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----------------
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# Run the demo
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LD_LIBRARY_PATH=/tmp/b/sandbox ./demo
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# Run the demo (static version)
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./demo_static
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# Run the boot example (requires disk image at /home/sglass/u/mmc1.img)
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LD_LIBRARY_PATH=/tmp/b/sandbox ./boot
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# Run the boot example (static version)
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./boot_static
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Key Points
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----------
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- Files are compiled with U-Boot headers by default, except those listed in
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sys-objs which use system headers
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- Use ulib_init() to init the library
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- Use ulib_uninit() to clean up
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- Set LD_LIBRARY_PATH when running dynamically linked programs
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- Each program automatically gets both dynamic and static versions built
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Copying for External Use
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-------------------------
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This directory can be copied elsewhere and used independently:
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cp -r examples/ulib ~/my-project/
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cd ~/my-project/ulib
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make UBOOT_BUILD=/path/to/u-boot-build srctree=/path/to/u-boot-source
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License
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-------
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All examples are licensed under GPL-2.0+
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