[PATCH v6 5/5] docs: Update custom_kernel docs for split up of kernel scripts and tools

[Stefan Koch <stefan-koch@siemens.com>]

Signed-off-by: Stefan Koch <stefan-koch@siemens.com>
---
 RECIPE-API-CHANGELOG.md | 31 +++++++++++++++++++++++++++++++
 doc/custom_kernel.md    | 18 +++++++++++-------
 2 files changed, 42 insertions(+), 7 deletions(-)

diff --git a/RECIPE-API-CHANGELOG.md b/RECIPE-API-CHANGELOG.md
index bea12871..def1e7f2 100644
--- a/RECIPE-API-CHANGELOG.md
+++ b/RECIPE-API-CHANGELOG.md
@@ -566,3 +566,34 @@ supported, but a warning is issued when it is used. Future versions will drop
 When building a custom kernel module, the `KBuild` file might be located in
 a subdirectory. To support this use-case, set `MODULE_DIR=$(PWD)/subdir` in
 the module build recipe.
+
+### Split up binaries from kernel headers to kbuild package for linux-custom
+
+Swap out the binaries from the kernel headers
+into kernel kbuild package.
+
+  * Split up binaries from kernel headers to kbuild package:
+    Introduce specific kernel kbuild packages that
+    ship the "scripts" and "tools" binaries.
+    The kernel headers fulfill this using symlinks to point
+    to the "scripts" and "tools" of the kernel kbuild package.
+
+  * Provide target and host specific kernel kbuild packages:
+    Introduce target and host specific kernel kbuild packages that
+    ship the "scripts" and "tools" binaries.
+
+    The "-kbuildtarget" and "-native" multiarch bitbake targets are useable to
+    run additional target or host specific builds for kbuild scripts and tools.
+
+    Using the "-kbuildtarget" bitbake target enables the build of
+    a target specific kbuild package at cross builds.
+    So using "linux-kbuild" provides the package for the target platform.
+
+    Using the "-native" bitbake target enables the build of
+    a host specific kbuild package at cross builds.
+    When cross building using "linux-kbuild-native"
+    provides the package for the host platform.
+
+    Only the "host" specific package is built automatically at cross builds.
+
+  * Support emulated module build with cross-compiled kernel for linux-module
diff --git a/doc/custom_kernel.md b/doc/custom_kernel.md
index 73987a5b..ce5f1bf7 100644
--- a/doc/custom_kernel.md
+++ b/doc/custom_kernel.md
@@ -38,12 +38,18 @@ The linux-custom recipe provides support for:
  7. Allow the name of the kernel image to be changed via `KERNEL_FILE` (defaults
     to `vmlinuz`)
 
- 8. Produce a `linux-headers` package which includes kernel headers and kbuild
-    scripts/tools
+ 8. Produce a `linux-headers` package which includes kernel headers
 
- 9. The `linux-headers` package shall support native and cross compiles of
-    out-of-tree kernel modules. However, when built in cross-compilation mode,
-    it cannot be used on the target so far.
+ 9. Produce a `linux-kbuild` package for both `target` and `host` arch
+    which includes kbuild scripts and tools.
+    Using `linux-kbuild` provides the package for the target and when
+    cross building `linux-kbuild-native` provides the package for the host.
+
+    So the `linux-headers` package supports native and cross compiles of
+    out-of-tree kernel modules. Even, when built in cross-compilation mode,
+    it can be used on the target using the `linux-kbuild` package.
+
+    Only the `host` specific package is built automatically at cross builds.
 
  10. Produce a `linux-libc-dev` package to support user-land builds
 
@@ -72,8 +78,6 @@ In the future, the recipe may be extended to:
 
  3. Be compatible with Ubuntu
 
- 4. When cross-building, generate kernel-headers for both host and target
-
 ## Examples
 
 The linux-custom recipe is currently used by the linux-mainline package and is
-- 
2.39.2