History

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.

Yann E. MORIN committed 13 years ago

Commit 0d8024c1 parent 422c8092 files · +20 −1Browse files

Unified · Split

2 files
  1. Documentation/kbuild/kconfig.txt +9 −0
  2. scripts/kconfig/conf.c +11 −1
Documentation/kbuild/kconfig.txt+9−0
@@ -89,6 +89,15 @@ These examples will disable most options (allnoconfig) but enable or · 88 unmodified lines
89disable the options that are explicitly listed in the specified89disable the options that are explicitly listed in the specified
90mini-config files.90mini-config files.
91 91
92______________________________________________________________________
93Environment variables for 'randconfig'
94
95KCONFIG_SEED
96--------------------------------------------------
97You can set this to the integer value used to seed the RNG, if you want
98to somehow debug the behaviour of the kconfig parser/frontends.
99If not set, the current time will be used.
100
92______________________________________________________________________101______________________________________________________________________
93Environment variables for 'silentoldconfig'102Environment variables for 'silentoldconfig'
94 103
scripts/kconfig/conf.c+11−1
@@ -13,6 +13,7 @@ · 12 unmodified lines
13#include <getopt.h>13#include <getopt.h>
14#include <sys/stat.h>14#include <sys/stat.h>
15#include <sys/time.h>15#include <sys/time.h>
16#include <errno.h>
16 17
17#include "lkc.h"18#include "lkc.h"
18 19
@@ -514,14 +515,23 @@ int main(int ac, char **av) · 495 unmodified lines
514 {515 {
515 struct timeval now;516 struct timeval now;
516 unsigned int seed;517 unsigned int seed;
518 char *seed_env;
517 519
518 /*520 /*
519 * Use microseconds derived seed,521 * Use microseconds derived seed,
520 * compensate for systems where it may be zero522 * compensate for systems where it may be zero
521 */523 */
522 gettimeofday(&now, NULL);524 gettimeofday(&now, NULL);
523
524 seed = (unsigned int)((now.tv_sec + 1) * (now.tv_usec + 1));525 seed = (unsigned int)((now.tv_sec + 1) * (now.tv_usec + 1));
526
527 seed_env = getenv("KCONFIG_SEED");
528 if( seed_env && *seed_env ) {
529 char *endp;
530 int tmp = (int)strtol(seed_env, &endp, 10);
531 if (*endp == '\0') {
532 seed = tmp;
533 }
534 }
525 srand(seed);535 srand(seed);
526 break;536 break;
527 }537 }