init.h: add some more documentation to __ref* tags

The __ref* tags may have been confusing for new kernel
developers (I was confused by them for sure) so adding a few
more sentences to comment to clear things up for people who
see those for the first time.

Signed-off-by: Michal Nazarewicz <m.nazarewicz@samsung.com>
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Michal Nazarewicz 2010-08-12 17:43:56 +02:00 committed by Greg Kroah-Hartman
parent c9bfff9c98
commit 5ea081785d

View File

@ -46,16 +46,23 @@
#define __exitdata __section(.exit.data)
#define __exit_call __used __section(.exitcall.exit)
/* modpost check for section mismatches during the kernel build.
/*
* modpost check for section mismatches during the kernel build.
* A section mismatch happens when there are references from a
* code or data section to an init section (both code or data).
* The init sections are (for most archs) discarded by the kernel
* when early init has completed so all such references are potential bugs.
* For exit sections the same issue exists.
*
* The following markers are used for the cases where the reference to
* the *init / *exit section (code or data) is valid and will teach
* modpost not to issue a warning.
* The markers follow same syntax rules as __init / __initdata. */
* modpost not to issue a warning. Intended semantics is that a code or
* data tagged __ref* can reference code or data from init section without
* producing a warning (of course, no warning does not mean code is
* correct, so optimally document why the __ref is needed and why it's OK).
*
* The markers follow same syntax rules as __init / __initdata.
*/
#define __ref __section(.ref.text) noinline
#define __refdata __section(.ref.data)
#define __refconst __section(.ref.rodata)