From: Vincent Jardin Date: Wed, 15 Jul 2026 16:57:16 +0000 (+0200) Subject: doc: usage: cmd: load: null-block-device X-Git-Tag: v2026.10-rc1~3^2~1 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c23eeeadfc4a2f351f056bc1d12b210a5fb9c3e9;p=thirdparty%2Fu-boot.git doc: usage: cmd: load: null-block-device Document the dispatch path added by the former commit fs: dispatch null_dev_desc_ok filesystems before lookup Add a null-block-device interfaces section that: * lists the three fstypes that can benefit of it (semihosting, ubifs, sandbox) and the CONFIG option that builds each * explains the '-' convention for the unused field Suggested-by: Simon Glass Signed-off-by: Vincent Jardin Reviewed-by: Simon Glass --- diff --git a/doc/usage/cmd/load.rst b/doc/usage/cmd/load.rst index bfa45c6f36c..bf2fffbed21 100644 --- a/doc/usage/cmd/load.rst +++ b/doc/usage/cmd/load.rst @@ -63,6 +63,39 @@ Example 16 bytes read in 1 ms (15.6 KiB/s) => +Null-block-device interfaces +---------------------------- + +A few ```` values have no underlying block device. Their +filesystem implementations directly call a back-end (JTAG +debugger, UBI volume, host running U-Boot under sandbox, ...) and +ignore the ```` field, which may be given as ``-``. So +``load - `` works. + +semihosting + Read files from the host filesystem of an attached JTAG debugger + using the ARM semihosting protocol. Useful with OpenOCD. + Built when ``CONFIG_SEMIHOSTING=y``. + +ubifs + Read files from a UBIFS volume that has already been attached + and mounted with the ``ubi part`` + ``ubifsmount`` commands. + Built when ``CONFIG_CMD_UBIFS=y``. + +sandbox + Read files from the host filesystem the sandbox binary is + running under. Available on sandbox builds. + +The ```` argument is conventionally written as ``-`` for +these interfaces, to make it visible at the call site that the field +is unused. The filesystem layer never looks at it. + +Example:: + + => load semihosting - ${kernel_addr_r} kernel.itb + 9437184 bytes read in 412 ms (21.8 MiB/s) + => + Configuration -------------