cmd: pxe: add support for FIT config selection

Add a way in configuration files (exlinux.conf for sysboot command)
to select a specific FIT configuration. The configuration is selected
with a string added after the FIT filename in the label "KERNEL" or
"LINUX", using the same format than bootm command:

KERNEL [Filename]#<conf>[#<extra-conf[#...]]

This configuration string, beginning by '#', is directly appended
to bootm argument 1 after <kernel_addr_r>.

bootm [<kernel_addr_r>]#<conf>[#<extra-conf[#...]]

see doc/uImage.FIT/command_syntax_extensions.txt for details

Example :
 KERNEL /fit.itb#cfg1
 KERNEL /fit.itb#cfg2

Configuration can be use also for overlay management :
 KERNEL /fit.itb#cfg1#dtbo1#dtbo3

see doc/uImage.FIT/overlay-fdt-boot.txt for details

Signed-off-by: Patrick Delaunay <patrick.delaunay@st.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/doc/README.pxe b/doc/README.pxe
index 98862cdfde..42f913c61f 100644
--- a/doc/README.pxe
+++ b/doc/README.pxe
@@ -140,6 +140,13 @@ kernel <path>	    - if this label is chosen, use tftp to retrieve the kernel
                       (or FIT image) at <path>. it will be stored at the address
                       indicated in the kernel_addr_r environment variable, and
                       that address will be passed to bootm to boot this kernel.
+                      For FIT image, The configuration specification can be
+                      appended to the file name, with the format:
+                        <path>#<conf>[#<extra-conf[#...]]
+                      It will passed to bootm with that address.
+                      (see: doc/uImage.FIT/command_syntax_extensions.txt)
+                      It useful for overlay selection in pxe file
+                      (see: doc/uImage.FIT/overlay-fdt-boot.txt)
 
 append <string>     - use <string> as the kernel command line when booting this
                       label.