[PATCH 8/8] kconfig: implement KCONFIG_PROBABILITY for randconfig

Yann E. MORIN
2013-04-24T22:30:50Z

From: "Yann E. MORIN" <yann.morin.1998@free.fr>

Currently the odds to set each symbol is (rounded):
booleans: y: 50% n: 50%
tristates: y: 33% m: 33% n: 33%

Introduce a KCONFIG_PROBABILITY environment variable to tweak the
probabilities (in percentage), as such:
KCONFIG_PROBABILITY y:n split y:m:n split
-----------------------------------------------------------------
[1] unset or empty 50 : 50 33 : 33 : 34
[2] N N : 100-N N/2 : N/2 : 100-N
N:M N+M : 100-(N+M) N : M : 100-(N+M)
N:M:L N : 100-N M : L : 100-(M+L)

[1] The current behaviour is kept as default, for backward compatibility
[2] The solution initially implemented by Peter for Buildroot, see:
http://git.buildroot.org/buildroot/commit/?id=3435c1afb5

Signed-off-by: Peter Korsgaard <jacmet@uclibc.org>
[yann.morin.1998@free.fr: add to Documentation/]
Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
---
Documentation/kbuild/kconfig.txt | 27 ++++++++++++++++++
scripts/kconfig/confdata.c | 57 ++++++++++++++++++++++++++++++++++++--
2 files changed, 81 insertions(+), 3 deletions(-)

diff --git a/Documentation/kbuild/kconfig.txt b/Documentation/kbuild/kconfig.txt
index dbf746b..3f429ed 100644
--- a/Documentation/kbuild/kconfig.txt
+++ b/Documentation/kbuild/kconfig.txt
@@ -98,6 +98,33 @@ 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.

+KCONFIG_PROBABILITY
+--------------------------------------------------
+This variable can be used to skew the probabilities. This variable can
+be unset or empty, or set to three different formats:
+ KCONFIG_PROBABILITY y:n split y:m:n split
+ -----------------------------------------------------------------
+ unset or empty 50 : 50 33 : 33 : 34
+ N N : 100-N N/2 : N/2 : 100-N
+ [1] N:M N+M : 100-(N+M) N : M : 100-(N+M)
+ [2] N:M:L N : 100-N M : L : 100-(M+L)
+
+where N, M and L are integers (in base 10) in the range [0,100], and so
+that:
+ [1] N+M is in the range [0,100]
+ [2] M+L is in the range [0,100]
+
+Examples:
+ KCONFIG_PROBABILITY=10
+ 10% of booleans will be set to 'y', 90% to 'n'
+ 5% of tristates will be set to 'y', 5% to 'm', 90% to 'n'
+ KCONFIG_PROBABILITY=15:25
+ 40% of booleans will be set to 'y', 60% to 'n'
+ 15% of tristates will be set to 'y', 25% to 'm', 60% to 'n'
+ KCONFIG_PROBABILITY=10:15:15
+ 10% of booleans will be set to 'y', 90% to 'n'
+ 15% of tristates will be set to 'y', 15% to 'm', 70% to 'n'
+
______________________________________________________________________
Environment variables for 'silentoldconfig'

diff --git a/scripts/kconfig/confdata.c b/scripts/kconfig/confdata.c
index 8927480..fc45fc1 100644
--- a/scripts/kconfig/confdata.c
+++ b/scripts/kconfig/confdata.c
@@ -1107,7 +1107,51 @@ static void set_all_choice_values(struct symbol *csym)
void conf_set_all_new_symbols(enum conf_def_mode mode)
{
struct symbol *sym, *csym;
- int i, cnt;
+ int i, cnt, pby, pty, ptm; /* pby: probability of boolean = y
+ * pty: probability of tristate = y
+ * ptm: probability of tristate = m
+ */
+
+ pby = 50; pty = ptm = 33; /* can't go as the default in switch-case
+ * below, otherwise gcc whines about
+ * -Wmaybe-uninitialized */
+ if (mode == def_random) {
+ int n, p[3];
+ char *env = getenv("KCONFIG_PROBABILITY");
+ n = 0;
+ while( env && *env ) {
+ char *endp;
+ int tmp = strtol( env, &endp, 10 );
+ if( tmp >= 0 && tmp <= 100 ) {
+ p[n++] = tmp;
+ } else {
+ errno = ERANGE;
+ perror( "KCONFIG_PROBABILITY" );
+ exit( 1 );
+ }
+ env = (*endp == ':') ? endp+1 : endp;
+ if( n >=3 ) {
+ break;
+ }
+ }
+ switch( n ) {
+ case 1:
+ pby = p[0]; ptm = pby/2; pty = pby-ptm;
+ break;
+ case 2:
+ pty = p[0]; ptm = p[1]; pby = pty + ptm;
+ break;
+ case 3:
+ pby = p[0]; pty = p[1]; ptm = p[2];
+ break;
+ }
+
+ if( pty+ptm > 100 ) {
+ errno = ERANGE;
+ perror( "KCONFIG_PROBABILITY" );
+ exit( 1 );
+ }
+ }

for_all_symbols(i, sym) {
if (sym_has_value(sym) || (sym->flags & SYMBOL_VALID))
@@ -1126,8 +1170,15 @@ void conf_set_all_new_symbols(enum conf_def_mode mode)
sym->def[S_DEF_USER].tri = no;
break;
case def_random:
- cnt = sym->type == S_TRISTATE ? 3 : 2;
- sym->def[S_DEF_USER].tri = (tristate)(rand() % cnt);
+ sym->def[S_DEF_USER].tri = no;
+ cnt = rand() % 100;
+ if (sym->type == S_TRISTATE) {
+ if (cnt < pty)
+ sym->def[S_DEF_USER].tri = yes;
+ else if (cnt < (pty+ptm))
+ sym->def[S_DEF_USER].tri = mod;
+ } else if (cnt < pby)
+ sym->def[S_DEF_USER].tri = yes;
break;
default:
continue;
--
1.7.10.4