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kconfig: allow specifying the seed for randconfig 

For reproducibility, it can be useful to be able to specify the
seed to use to seed the RNG.

Add a new KCONFIG_SEED environment variable which can be set to
the seed to use:
    $ make KCONFIG_SEED=42 randconfig
    $ sha1sum .config
    70a128c8dcc61303069e1be352cce64114dfcbca  .config
    $ make KCONFIG_SEED=42 randconfig
    $ sha1sum .config
    70a128c8dcc61303069e1be352cce64114dfcbca  .config

It's very usefull for eg. debugging the kconfig parser.

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
This commit is contained in:
Yann E. MORIN 2013-04-13 22:49:13 +02:00
parent 422c809f03
commit 0d8024c6eb
2 changed files with 20 additions and 1 deletions
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9
Documentation/kbuild/kconfig.txt
View File

@ -89,6 +89,15 @@ These examples will disable most options (allnoconfig) but enable or
disable the options that are explicitly listed in the specified disable the options that are explicitly listed in the specified
mini-config files. mini-config files.
______________________________________________________________________
Environment variables for 'randconfig'
KCONFIG_SEED
--------------------------------------------------
You can set this to the integer value used to seed the RNG, if you want
to somehow debug the behaviour of the kconfig parser/frontends.
If not set, the current time will be used.
______________________________________________________________________ ______________________________________________________________________
Environment variables for 'silentoldconfig' Environment variables for 'silentoldconfig'

12
scripts/kconfig/conf.c
View File

@ -13,6 +13,7 @@
#include <getopt.h> #include <getopt.h>
#include <sys/stat.h> #include <sys/stat.h>
#include <sys/time.h> #include <sys/time.h>
#include <errno.h>
#include "lkc.h" #include "lkc.h"
@ -514,14 +515,23 @@ int main(int ac, char **av)
{ {
struct timeval now; struct timeval now;
unsigned int seed; unsigned int seed;
char *seed_env;
/* /*
* Use microseconds derived seed, * Use microseconds derived seed,
* compensate for systems where it may be zero * compensate for systems where it may be zero
*/ */
gettimeofday(&now, NULL); gettimeofday(&now, NULL);
seed = (unsigned int)((now.tv_sec + 1) * (now.tv_usec + 1)); seed = (unsigned int)((now.tv_sec + 1) * (now.tv_usec + 1));
seed_env = getenv("KCONFIG_SEED");
if( seed_env && *seed_env ) {
char *endp;
int tmp = (int)strtol(seed_env, &endp, 10);
if (*endp == '\0') {
seed = tmp;
}
}
srand(seed); srand(seed);
break; break;
} }