ref-manual: add FIT_KERNEL_COMP_ALG*

Add FIT_KERNEL_COMP_ALG and FIT_KERNEL_COMP_ALG_EXTENSION. Examining
OE-Core commit 5c72105e2973e613b5c0f0e6310ffdea6e56c6c7 and the
associated code, these do not enable arbitrary selection of compression
algorithm - only disabling compression - so document them accordingly.

(From yocto-docs rev: 41640526dd87153fdf802b058336c6fb466b8ade)

Signed-off-by: Paul Eggleton <paul.eggleton@microsoft.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/documentation/ref-manual/variables.rst b/documentation/ref-manual/variables.rst
index 153c60cd2c..8f059650d3 100644
--- a/documentation/ref-manual/variables.rst
+++ b/documentation/ref-manual/variables.rst
@@ -2580,6 +2580,16 @@ system and gives an overview of their function and contents.
    :term:`FIT_HASH_ALG`
       Specifies the hash algorithm used in creating the FIT Image. For e.g. sha256.
 
+   :term:`FIT_KERNEL_COMP_ALG`
+      Compression algorithm to use for the kernel image inside the FIT Image.
+      At present, the only supported values are "gzip" (default) or "none"
+      If you set this variable to anything other than "none" you may also need
+      to set :term:`FIT_KERNEL_COMP_ALG_EXTENSION`.
+
+   :term:`FIT_KERNEL_COMP_ALG_EXTENSION`
+      File extension corresponding to :term:`FIT_KERNEL_COMP_ALG`. The default
+      value is ".gz".
+
    :term:`FIT_KEY_GENRSA_ARGS`
       Arguments to openssl genrsa for generating RSA private key for signing
       fitImage. The default value is "-F4". i.e. the public exponent 65537 to