[PATCH] user_manual.md: add a machine kernel support section

[chris....@siemens.com]

From: Christopher Larson <chris....@siemens.com>

This is quite simple for now, only mentioning KERNEL_NAME and
KERNEL_NAMES. KERNEL_IMAGE was already mentioned in the previous
section.

Signed-off-by: Christopher Larson <chris....@siemens.com>
---
doc/user_manual.md | 15 +++++++++++++++
1 file changed, 15 insertions(+)

diff --git a/doc/user_manual.md b/doc/user_manual.md
index 845823bb..cb9f5551 100644
--- a/doc/user_manual.md
+++ b/doc/user_manual.md
@@ -597,6 +597,21 @@ ## Add a New Machine

---

+### Kernel Support
+
+A machine can be configured to support a specific kernel recipe by setting the `KERNEL_NAME` variable, and may be configured to support multiple kernels by using the `KERNEL_NAMES` variable in addition. The latter is optional, and also enables generating packages like external kernel modules for all specified kernel variants.
+
+For example, in your machine configuration:
+
+```bitbake
+KERNEL_NAME = "linux-mainline"
+KERNEL_NAMES = "linux-mainline linux-cip"
+```
+
+When `KERNEL_NAMES` is set, recipes inheriting the `per-kernel` class will generate variants for each listed kernel. Installation of each must be explicitly handled in the image.
+
+---
+
## Add a New Image

Image in Isar contains the following artifacts:
--
2.48.1

[Christopher Larson]

On 5/7/2025 9:53 AM, chris....@siemens.com wrote:
> From: Christopher Larson <chris....@siemens.com>
>
> This is quite simple for now, only mentioning KERNEL_NAME and
> KERNEL_NAMES. KERNEL_IMAGE was already mentioned in the previous
> section.

Forgot to mention that this mentions a variable used in per_kernel, so
should probably go after that series. I recognize it's a bit simplistic,
but the docs are currently pretty minimal about MACHINE configuration
maintenance.
--
Christopher Larson
Siemens AG
www.siemens.com