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authorYann E. MORIN <yann.morin.1998@free.fr>2013-04-14 00:49:13 +0400
committerYann E. MORIN <yann.morin.1998@free.fr>2013-04-25 02:16:25 +0400
commit0d8024c6ebadb68f1154377c2e1996b4e649e4c8 (patch)
treebd38ec60a908adf8cf7c75aa7b3b19fab52d9e64
parent422c809f03f043d0950d8362214818e956a9daee (diff)
downloadlinux-0d8024c6ebadb68f1154377c2e1996b4e649e4c8.tar.xz
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>
-rw-r--r--Documentation/kbuild/kconfig.txt9
-rw-r--r--scripts/kconfig/conf.c12
2 files changed, 20 insertions, 1 deletions
diff --git a/Documentation/kbuild/kconfig.txt b/Documentation/kbuild/kconfig.txt
index b8b77bbc784f..dbf746b70553 100644
--- a/Documentation/kbuild/kconfig.txt
+++ b/Documentation/kbuild/kconfig.txt
@@ -90,6 +90,15 @@ disable the options that are explicitly listed in the specified
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'
KCONFIG_NOSILENTUPDATE
diff --git a/scripts/kconfig/conf.c b/scripts/kconfig/conf.c
index e39fcd8143ea..bde5b95c8c19 100644
--- a/scripts/kconfig/conf.c
+++ b/scripts/kconfig/conf.c
@@ -13,6 +13,7 @@
#include <getopt.h>
#include <sys/stat.h>
#include <sys/time.h>
+#include <errno.h>
#include "lkc.h"
@@ -514,14 +515,23 @@ int main(int ac, char **av)
{
struct timeval now;
unsigned int seed;
+ char *seed_env;
/*
* Use microseconds derived seed,
* compensate for systems where it may be zero
*/
gettimeofday(&now, NULL);
-
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);
break;
}