docs: document new convention for Kconfig board symbols

Boards have been switched to use "default y" and are now listed
in default-configs/*.mak only for convenience.

Document this change and the new possibilities that it allows.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Paolo Bonzini 2024-03-11 11:02:17 +01:00
parent 0a12e7b752
commit 7cdfcea693

View file

@ -211,6 +211,8 @@ declares its dependencies in different ways:
config SUN4M
bool
default y
depends on SPARC && !SPARC64
imply TCX
imply CG3
select CS4231
@ -228,8 +230,16 @@ declares its dependencies in different ways:
directives. A device should be listed under ``select`` if the board
cannot be started at all without it. It should be listed under
``imply`` if (depending on the QEMU command line) the board may or
may not be started without it. Boards also default to false; they are
enabled by the ``default-configs/*.mak`` for the target they apply to.
may not be started without it. Boards default to true, but also
have a ``depends on`` clause to limit them to the appropriate targets.
For some targets, not all boards may be supported by hardware
virtualization, in which case they also depend on the ``TCG`` symbol,
Other symbols that are commonly used as dependencies for boards
include libraries (such as ``FDT``) or ``TARGET_BIG_ENDIAN``
(possibly negated).
Boards are listed for convenience in the ``default-configs/*.mak``
for the target they apply to.
**internal elements**