kbuld: Implement oldmodconfig

While verifying that my user namespace patches are as complete as I expect them to be I came a came across the need to build kernel configurations with a few choice settings disabled and everything else enabled. Adding a make oldmodconfig made generating those configurations straight forward, as now I can set the options I care about and the oldmodconfig can answering everything else for me in a consistent way.

Dne 24.4.2012 02:59, Eric W. Biederman napsal(a):

Quoted 8 lines

While verifying that my user namespace patches are as complete as I expect them to be I came a came across the need to build kernel configurations with a few choice settings disabled and everything else enabled. Adding a make oldmodconfig made generating those configurations straight forward, as now I can set the options I care about and the oldmodconfig can answering everything else for me in a consistent way.

Doesn't

KCONFIG_ALLCONFIG=base.config make allmodconfig

do the same thing? If not, the difference should be explained in the changelog.

Quoted 11 lines · Eric W. Biederman

scripts/kconfig/conf.c +7 -2

 		name = getenv("KCONFIG_ALLCONFIG");
-		if (name && !stat(name, &tmpstat)) {
-			conf_read_simple(name, S_DEF_USER);
+		if (name && name[0] != '\0') {
+			if (conf_read_simple(name, S_DEF_USER)) {
+				fprintf(stderr,
+					_("*** Can't read seed configuration \"%s\"!\n"),
+					name);
+				exit(1);
+			}
 			break;

scripts/kconfig/conf.c int main(int ac, char **av) · line 589

Quoted 2 lines

scripts/kconfig/conf.c +0 -0

 		}
 		switch (input_mode) {

Before this patch, the code would fall back to a file named all{no,yes,mod,def,random}.config and then to all.config. Now you require $KCONFIG_ALLCONFIG to always be a file. I suggest we keep the fallback at least for KCONFIG_ALLCONFIG=1, like this:

scripts/kconfig/conf.c +18 -7

index f208f90..36efc8f 100644
@@ -574,9 +574,17 @@ int main(int ac, char **av)
 	case alldefconfig:
 	case randconfig:
 		name = getenv("KCONFIG_ALLCONFIG");
-		if (name && !stat(name, &tmpstat)) {
-			conf_read_simple(name, S_DEF_USER);
-			break;
+		if (name && name[0] != '\0') {
+			if (conf_read_simple(name, S_DEF_USER)) {
+				if (strcmp(name, "1") != 0) {
+					fprintf(stderr,
+						_("*** Can't read seed configuration \"%s\"!\n"),
+						name);
+					exit(1);
+				}
+			} else {
+				break;
+			}
 		}
 		switch (input_mode) {
 		case allnoconfig:	name = "allno.config"; break;

@@ -586,10 +594,13 @@ int main(int ac, char **av)
 		case randconfig:	name = "allrandom.config"; break;
 		default: break;
 		}
-		if (!stat(name, &tmpstat))
-			conf_read_simple(name, S_DEF_USER);
-		else if (!stat("all.config", &tmpstat))
-			conf_read_simple("all.config", S_DEF_USER);
+		if (conf_read_simple(name, S_DEF_USER) &&
+				conf_read_simple("all.config", S_DEF_USER)) {
+			fprintf(stderr,
+				_("*** KCONFIG_ALLCONFIG=1 set, but no \"%s\" or \"all.config\" file found\n"),
+				name);
+			exit(1);
+		}
 		break;
 	default:
 		break;

And update Documentation/kbuild/kconfig.txt.

Michal

Quoted 12 lines · Michal Marek

Quoted 11 lines · Eric W. Biederman

scripts/kconfig/conf.c +7 -2

 		name = getenv("KCONFIG_ALLCONFIG");
-		if (name && !stat(name, &tmpstat)) {
-			conf_read_simple(name, S_DEF_USER);
+		if (name && name[0] != '\0') {
+			if (conf_read_simple(name, S_DEF_USER)) {
+				fprintf(stderr,
+					_("*** Can't read seed configuration \"%s\"!\n"),
+					name);
+				exit(1);
+			}
 			break;

Quoted 8 lines

scripts/kconfig/conf.c int main(int ac, char **av) · line 589

Quoted 2 lines

scripts/kconfig/conf.c +0 -0

 		}
 		switch (input_mode) {

Before this patch, the code would fall back to a file named all{no,yes,mod,def,random}.config and then to all.config. Now you require $KCONFIG_ALLCONFIG to always be a file. I suggest we keep the fallback at least for KCONFIG_ALLCONFIG=1, like this:

I don't require KCONFIG_ALLCONFIG to always be a file if it is an empty string we continue to fallback to the predefined file names. Which is the currently documented behavior.

As for KCONFIG_ALLCONFIG=1 if people are a actually doing that the complexity seems worth it (to not break muscle memory and/or scripts). I was just aiming for an absolutely trivial and simple implementation.

Why do you think people have been specifying KCONFIG_ALLCONFIG=1? instead of simply exporting KCONFIG_ALLCONFIG with an empty string?

- Only try to read the file specified if KCONFIG_ALL_CONFIG is set to something other than the empty string or "1".

- Don't use stat to check the name passed to conf_read_simple so that zconf_fopen can find the file in the current directory or in SRCTREE removing a extremely source of confusing failure, where KCONFIG_ALL_CONFIG was not interpreted with respect to the directory make was called in.

- If conf_read_simple fails complain clearly and stop processing. Allowing the simple debugging of typos.

- Clearly document the behavior so it is clear to users which values are treated as flags and which values are treated as filenames.