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SubjectRe: [PATCH] kconfig: redo fake deps at include/config/*.h
On Thu, Apr 15, 2021 at 7:01 AM Alexey Dobriyan <adobriyan@gmail.com> wrote:
>
> Make include/config/foo/bar.h fake deps files generation simpler.
>
> * delete .h suffix
> those aren't header files, shorten filenames,
>
> * delete tolower()
> Linux filesystems can deal with both upper and lowercase
> filenames very well,
>
> * put everything in 1 directory
> Presumably 'mkdir -p' split is from dark times when filesystems
> handled huge directories badly, disks were round adding to
> seek times.


I am not sure about the impact of this change
given various file systems in the wild,
but this simplification is attractive.

With a quick search, I found a comment
'performance issues past 10,000' on ext2 [1]
but that may not be what we care about much...

[1]: https://webmasters.stackexchange.com/questions/99539/what-is-a-recommended-maximum-number-of-files-in-a-directory-on-your-webserver





> @@ -124,36 +124,12 @@ static void xprintf(const char *format, ...)
> va_end(ap);
> }
>
> -static void xputchar(int c)
> -{
> - int ret;
> -
> - ret = putchar(c);
> - if (ret == EOF) {
> - perror("fixdep");
> - exit(1);
> - }
> -}
> -
> /*
> * Print out a dependency path from a symbol name
> */
> static void print_dep(const char *m, int slen, const char *dir)
> {
> - int c, prev_c = '/', i;
> -
> - xprintf(" $(wildcard %s/", dir);
> - for (i = 0; i < slen; i++) {
> - c = m[i];
> - if (c == '_')
> - c = '/';
> - else
> - c = tolower(c);
> - if (c != '/' || prev_c != '/')
> - xputchar(c);
> - prev_c = c;
> - }
> - xprintf(".h) \\\n");
> + xprintf(" $(wildcard %s/%.*s) \\\n", dir, slen, m);



Since this function now contains just one line,
can you hard-code

xprintf(" $(wildcard include/config/%.*s) \\\n", slen, m);

in use_config() ?



> }
>
> struct item {
> --- a/scripts/kconfig/confdata.c
> +++ b/scripts/kconfig/confdata.c
> @@ -130,19 +130,14 @@ static size_t depfile_prefix_len;
> static int conf_touch_dep(const char *name)
> {
> int fd, ret;
> - const char *s;
> - char *d, c;
> + char *d;
>
> /* check overflow: prefix + name + ".h" + '\0' must fit in buffer. */
> if (depfile_prefix_len + strlen(name) + 3 > sizeof(depfile_path))

Since you dropped the ".h" suffix,
please fix up this line.





Also, you can fix

# changed, Kconfig touches the corresponding timestamp file
include/config/*.h.

in kernel/gen_kheaders.sh





> return -1;
>
> d = depfile_path + depfile_prefix_len;
> - s = name;
> -
> - while ((c = *s++))
> - *d++ = (c == '_') ? '/' : tolower(c);
> - strcpy(d, ".h");
> + strcpy(d, name);
>
> /* Assume directory path already exists. */
> fd = open(depfile_path, O_WRONLY | O_CREAT | O_TRUNC, 0644);
> @@ -465,7 +460,7 @@ int conf_read_simple(const char *name, int def)
> * Reading from include/config/auto.conf
> * If CONFIG_FOO previously existed in
> * auto.conf but it is missing now,
> - * include/config/foo.h must be touched.
> + * include/config/FOO must be touched.
> */
> conf_touch_dep(line + strlen(CONFIG_));
> else



--
Best Regards
Masahiro Yamada

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