doc: qfw man-page
Provide a man-page for the qfw command.
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
diff --git a/doc/usage/qfw.rst b/doc/usage/qfw.rst
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+.. SPDX-License-Identifier: GPL-2.0+
+
+qfw command
+===========
+
+Synopsis
+--------
+
+::
+
+ qfw list
+ qfw cpus
+ qfw load [kernel_addr [initrd_addr]]
+
+Description
+-----------
+
+The *qfw* command is used to retrieve information form the QEMU firmware.
+
+The *qfw list* sub-command displays the QEMU firmware files.
+
+The *qfw cpus* sub-command displays the available CPUs.
+
+The *qfw load* command is used to load a kernel and an initial RAM disk.
+
+kernel_addr
+ address to which the file specified by the -kernel parameter of QEMU shall
+ be loaded. Defaults to environment variable *loadaddr* and further to
+ the value of *CONFIG_LOADADDR*.
+
+initrd_addr
+ address to which the file specified by the -initrd parameter of QEMU shall
+ be loaded. Defaults to environment variable *ramdiskaddr* and further to
+ the value of *CONFIG_RAMDISK_ADDR*.
+
+Examples
+--------
+
+QEMU firmware files are listed via the *qfw list* command:
+
+::
+
+ => qfw list
+ etc/boot-fail-wait
+ etc/smbios/smbios-tables
+ etc/smbios/smbios-anchor
+ etc/e820
+ genroms/kvmvapic.bin
+ genroms/linuxboot.bin
+ etc/system-states
+ etc/acpi/tables
+ etc/table-loader
+ etc/tpm/log
+ etc/acpi/rsdp
+ bootorder
+
+The available CPUs can be shown via the *qfw cpus* command:
+
+::
+
+ => qfw cpu
+ 2 cpu(s) online
+
+The *-kernel* and *-initrd* parameters allow to specify a kernel and an
+initial RAM disk for QEMU:
+
+.. code-block:: bash
+
+ $ qemu-system-x86_64 -machine pc-i440fx-2.5 -bios u-boot.rom -m 1G \
+ -nographic -kernel vmlinuz -initrd initrd
+
+Now the kernel and the initial RAM disk can be loaded to the U-Boot memory via
+the *qfw load* command and booted thereafter.
+
+::
+
+ => qfw load ${kernel_addr_r} ${ramdisk_addr_r}
+ loading kernel to address 0000000001000000 size 5048f0 initrd 0000000004000000 size 3c94891
+ => zboot 1000000 5048f0 4000000 3c94891
+ Valid Boot Flag
+ Magic signature found
+ Linux kernel version 4.19.0-14-amd64 (debian-kernel@lists.debian.org) #1 SMP Debian 4.19.171-2 (2021-01-30)
+ Building boot_params at 0x00090000
+ Loading bzImage at address 100000 (5260160 bytes)
+
+Configuration
+-------------
+
+The qfw command is only available if CONFIG_CMD_QFW=y.