On 18.5.2011 08:23, Arnaud Lacombe wrote:
Hi,
[added Valdis.Kletnieks@xxxxxx to CC:]
On Tue, May 17, 2011 at 3:53 PM, Sam Ravnborg<sam@xxxxxxxxxxxx> wrote:
On Tue, May 17, 2011 at 05:35:32PM +0200, Michal Marek wrote:
For strings and integers, the config_is_xxx macros are useless and
sometimes misleading:
#define CONFIG_INITRAMFS_SOURCE ""
#define config_is_initramfs_source() 1
I'm late with this comment....
Could we introduce "config_is_foo" using a syntax that
does not break grepability?
Maybe a syntax like this?
#ifdef CONFIG_FOO
and
if (KCONFIG_FOO())
Grepping for the use of a symbol is a very typical thing,
so we should try to keep this.
And with the suggested syntax above I expect fixdep to
catch up both usage types.
Actually, there is already an issue, on a much smaller scale, in the
current tree with NUMA_BUILD and COMPACTION_BUILD. The real way to fix
this would be to always defines CONFIG_FOO, its value being 1 or 0
depending on whether or not the symbol is selected. This is a
+35k/-35k change.
Also, I find KCONFIG_FOO() is too specific to be in the kernel source,
and redundant with CONFIG_FOO.
I've been playing a bit with the preprocessor, and reached that point:
#define EXPAND(x) __ ## x
#define CONFIGURED(x) \
({ int __1 __maybe_unused = 1; \
int __ ## x __maybe_unused = 0; \
EXPAND(x); })
I am not specifically proud of that, use case would be:
extern func(void);
int fn()
{
if(CONFIGURED(CONFIG_FOO))
func();
}
I finally got round to revisit this. Your approach inspired me to a much
simpler scheme: Instead of generating the config_is_xxx macros for
direct use in the code, name them __enabled_CONFIG_XXX or similar and
have a macro that expands given CONFIG_XXX symbol to the other form:
/*
* Usage: ENABLED(CONFIG_FOO)
* Please do not use the __enabled_CONFIG_FOO defines directly to not break
* grepability of the code.
*/
#define ENABLED(x) __enabled_ ## x
plus a checkpatch.pl check so that people do not use the
__enabled_CONFIG_FOO macros in their code. git grep -w CONFIG_FOO
continues to work, fixdep continues to work, it works with -O0 because
it expands to a if(1) or if(0). Am I missing some obvious problem?
Attached is my test program:
$ gcc -Wall -O0 test.c
$ ./a.out
Foo1.0
Foo1.1
$ strings ./a.out | grep Foo
Foo1.0
Foo1.1
Michal
#include <stdio.h>
#define CONFIG_FOO1 1
#undef CONFIG_FOO2
#define __enabled_CONFIG_FOO1 1
#define __enabled_CONFIG_FOO2 0
/*
* Usage: ENABLED(CONFIG_FOO)
* Please do not use the __enabled_CONFIG_FOO defines directly to not break
* grepability of the code.
*/
#define ENABLED(x) __enabled_ ## x
int main(void)
{
#ifdef CONFIG_FOO1
puts("Foo1.0");
#endif
#ifdef CONFIG_FOO2
puts("Foo2.0");
#endif
if (ENABLED(CONFIG_FOO1)) {
puts("Foo1.1");
}
if (ENABLED(CONFIG_FOO2)) {
puts("Foo2.1");
}
return 0;
}
