Existing sentence on cross-compilation that mentions ppc64 does not
make much sense in today's perspective.

Expand it for the benefits of testing against architectures of
different word sizes and endianness.

Signed-off-by: Akira Yokosawa <akiyks@gmail.com>
Reviewed-by: Randy Dunlap <redacted>
---
v2: Split out change in the English doc from v1 [1].
    Keep Randy's Rb tag (as it was meant for the change in English doc).

[1] https://lore.kernel.org/20250128102805.112691-2-akiyks@gmail.com/ (local)
--
 Documentation/process/submit-checklist.rst | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/Documentation/process/submit-checklist.rst b/Documentation/process/submit-checklist.rst
index e531dd504b6c..88b6358258d7 100644
--- a/Documentation/process/submit-checklist.rst
+++ b/Documentation/process/submit-checklist.rst

@@ -91,9 +91,12 @@ Build your code
      fix any issues.
 
 2) Builds on multiple CPU architectures by using local cross-compile tools
-   or some other build farm. Note that ppc64 is a good architecture for
-   cross-compilation checking because it tends to use ``unsigned long`` for
-   64-bit quantities.
+   or some other build farm.
+   Note that testing against architectures of different word sizes
+   (32- and 64-bit) and different endianness (big- and little-) is effective
+   in catching various portability issues due to false assumptions on
+   representable quantity range, data alignment, or endianness, among
+   others.