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kbuild: simplify dependency generation for CONFIG_TRIM_UNUSED_KSYMS

My main motivation of this commit is to clean up scripts/Kbuild.include and scripts/Makefile.build. Currently, CONFIG_TRIM_UNUSED_KSYMS works with a tricky gimmick; possibly exported symbols are detected by letting $(CPP) replace EXPORT_SYMBOL* with a special string '=== __KSYM_*===', which is post-processed by sed, and passed to fixdep. The extra preprocessing is costly, and hacking cmd_and_fixdep is ugly. I came up with a new way to find exported symbols; insert a dummy symbol __ksym_marker_* to each potentially exported symbol. Those dummy symbols are picked up by $(NM), post-processed by sed, then appended to .*.cmd files. I collected the post-process part to a new shell script scripts/gen_ksymdeps.sh for readability. The dummy symbols are put into the .discard.* section so that the linker script rips them off the final vmlinux or modules. A nice side-effect is building with CONFIG_TRIM_UNUSED_KSYMS will be much faster.

Masahiro Yamada committed 7 years ago

Commit bbda5ec1 parent ee3e46b6 files · +53 −69Browse files

Showing the changes to scripts/basic (1 of 6 files). Show all

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scripts/basic/fixdep.c+4−27
@@ -105,8 +105,7 @@ · 104 unmodified lines
105105
106106 static void usage(void)
107107 {
108− fprintf(stderr, "Usage: fixdep [-e] <depfile> <target> <cmdline>\n");
109− fprintf(stderr, " -e insert extra dependencies given on stdin\n");
108+ fprintf(stderr, "Usage: fixdep <depfile> <target> <cmdline>\n");
110109 exit(1);
111110 }
112111
@@ -131,21 +130,6 @@ static void print_dep(const char *m, int slen, const char *dir) · 18 unmodified lines
131130 printf(".h) \\\n");
132131 }
133132
134−static void do_extra_deps(void)
135−{
136− char buf[80];
137−
138− while (fgets(buf, sizeof(buf), stdin)) {
139− int len = strlen(buf);
140−
141− if (len < 2 || buf[len - 1] != '\n') {
142− fprintf(stderr, "fixdep: bad data on stdin\n");
143− exit(1);
144− }
145− print_dep(buf, len - 1, "include/ksym");
146− }
147−}
148−
149133 struct item {
150134 struct item *next;
151135 unsigned int len;
@@ -293,7 +277,7 @@ static int is_ignored_file(const char *s, int len) · 141 unmodified lines
293277 * assignments are parsed not only by make, but also by the rather simple
294278 * parser in scripts/mod/sumversion.c.
295279 */
296−static void parse_dep_file(char *m, const char *target, int insert_extra_deps)
280+static void parse_dep_file(char *m, const char *target)
297281 {
298282 char *p;
299283 int is_last, is_target;
@@ -369,9 +353,6 @@ static void parse_dep_file(char *m, const char *target, int insert_extra_deps) · 69 unmodified lines
369353 exit(1);
370354 }
371355
372− if (insert_extra_deps)
373− do_extra_deps();
374−
375356 printf("\n%s: $(deps_%s)\n\n", target, target);
376357 printf("$(deps_%s):\n", target);
377358 }
@@ -379,13 +360,9 @@ static void parse_dep_file(char *m, const char *target, int insert_extra_deps) · 1 unmodified line
379360 int main(int argc, char *argv[])
380361 {
381362 const char *depfile, *target, *cmdline;
382− int insert_extra_deps = 0;
383363 void *buf;
384364
385− if (argc == 5 && !strcmp(argv[1], "-e")) {
386− insert_extra_deps = 1;
387− argv++;
388− } else if (argc != 4)
365+ if (argc != 4)
389366 usage();
390367
391368 depfile = argv[1];
@@ -395,7 +372,7 @@ int main(int argc, char *argv[]) · 3 unmodified lines
395372 printf("cmd_%s := %s\n\n", target, cmdline);
396373
397374 buf = read_file(depfile);
398− parse_dep_file(buf, target, insert_extra_deps);
375+ parse_dep_file(buf, target);
399376 free(buf);
400377
401378 return 0;