[kbd] [PATCH] setleds: add option to reset state to the BIOS default

[kbd] [PATCH] setleds: add option to reset state to the BIOS default

[Petr Tesarik]

Hello Alexey and everybody,

please consider the following patch for kbd.

As you probably know, the Linux kernel resets the LED states to all off on 
boot. However, many users would like to keep the BIOS NumLock setting, and 
others get confused after they press one of the lock keys in the boot loader 
and it gets reset again when Linux initializes the terminal.

Because of that, many distros have used various ways to "improve" user 
experience: setting NumLock on by default, making OS-specific configuration 
options, or reading the BIOS area. The last option seems best to me, because 
it usually also preserves whatever you did in the boot loader. Unfortunately, 
there's no simple utility to read the state, so distros sometimes do insane 
things to get it (e.g. run hwinfo and grep only for the LED states and then 
run setleds with the appropriate arguments). Obviously, this approach isn't 
exactly fast...

Since setleds must be always used in the end, the most efficient solution is 
to add an option that resets the LED states to what they were before the Linux 
kernel booted.

Signed-off-by: Petr Tesarik <ptesarik@suse.cz>

---
 src/setleds.c |   64 
+++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 61 insertions(+), 3 deletions(-)

diff --git a/src/setleds.c b/src/setleds.c
index 3577aee..00e3151 100644
--- a/src/setleds.c
+++ b/src/setleds.c
@@ -11,18 +11,29 @@
 #include <fcntl.h>
 #include <linux/kd.h>
 #include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <unistd.h>
 #include "nls.h"
 #include "version.h"
 
+#if defined(__i386__) || defined(__x86_64__)
+# define HAVE_BIOS	1
+# define BIOS_KBD_ADDR	0x497
+# define BIOS_LED_SCR	0x01
+# define BIOS_LED_NUM	0x02
+# define BIOS_LED_CAP	0x04
+#endif
+
 static void attr_noreturn
 usage(void)
 {
     fprintf(stderr, _(
 "Usage:\n"
-"	setleds [-v] [-L] [-D] [-F] [[+|-][ num | caps | scroll %s]]\n"
+"	setleds [-v] [-L] [-D] [-F] [[+|-][ num | caps | scroll %s]%s]\n"
 "Thus,\n"
 "	setleds +caps -num\n"
 "will set CapsLock, clear NumLock and leave ScrollLock unchanged.\n"
+"%s"
 "The settings before and after the change (if any) are reported\n"
 "when the -v option is given or when no change is requested.\n"
 "Normally, setleds influences the vt flag settings\n"
@@ -32,9 +43,15 @@ usage(void)
 "that a subsequent reset will not change the flags.\n"
 ),
 #ifdef __sparc__
-    "| compose "
+    "| compose ",
+#else
+    "",
+#endif
+#ifdef HAVE_BIOS
+    " | bios ",
+"You can also specify \"bios\" to reset state to the BIOS default.\n"
 #else
-    ""
+    "", ""
 #endif
     );
     exit(1);
@@ -152,6 +169,40 @@ sunsetleds(arg_state char *cur_leds) {
 #endif
 }
 
+#ifdef HAVE_BIOS
+static void
+biosgetleds(char *cur_leds) {
+    int memfd;
+    long pagesz, mapoff;
+    char *map, bios_state;
+
+    memfd = open("/dev/mem", O_RDONLY);
+    if (memfd < 0) {
+	perror("/dev/mem");
+	fprintf(stderr, _("Error opening /dev/mem.\n"));
+	exit(1);
+    }
+    pagesz = sysconf(_SC_PAGESIZE);
+    mapoff = BIOS_KBD_ADDR & ~(pagesz-1);
+    map = mmap(NULL, pagesz, PROT_READ, MAP_SHARED, memfd, mapoff);
+    if (map == MAP_FAILED) {
+	perror("/dev/mem");
+	fprintf(stderr, _("Error mapping /dev/mem.\n"));
+	exit(1);
+    }
+    bios_state = map[BIOS_KBD_ADDR - mapoff];
+    *cur_leds = 0;
+    if (bios_state & BIOS_LED_SCR)
+	*cur_leds |= LED_SCR;
+    if (bios_state & BIOS_LED_NUM)
+	*cur_leds |= LED_NUM;
+    if (bios_state & BIOS_LED_CAP)
+	*cur_leds |= LED_CAP;
+    munmap(map, pagesz);
+    close(memfd);
+}
+#endif	/* HAVE_BIOS */
+
 int
 main(int argc, char **argv) {
     int optL = 0, optD = 0, optF = 0, verbose = 0;
@@ -241,6 +292,13 @@ main(int argc, char **argv) {
 
     while(--argc) {
 	ap = *++argv;
+#ifdef HAVE_BIOS
+	if (!strcmp(ap, "bios")) {
+	  biosgetleds(&nval);
+	  ndef = LED_NUM | LED_CAP | LED_SCR;
+	  goto nxtarg;
+	}
+#endif
 	sign = 1;		/* by default: set */
 	if(*ap == '+')
 	  ap++;

Re: [kbd] [PATCH] setleds: add option to reset state to the BIOS default

[Petr Tesarik]

Dne Čt 26. července 2012 21:49:05 Petr Tesarik napsal(a):
> Hello Alexey and everybody,
> 
> please consider the following patch for kbd.
>[...]
> +    bios_state = map[BIOS_KBD_ADDR - mapoff];
> +    *cur_leds = 0;
> +    if (bios_state & BIOS_LED_SCR)
> +	*cur_leds |= LED_SCR;
> +    if (bios_state & BIOS_LED_NUM)
> +	*cur_leds |= LED_NUM;
> +    if (bios_state & BIOS_LED_CAP)
> +	*cur_leds |= LED_CAP;

I've just noticed that this produces crappy code, especially given that the 
BIOS bits are numerically equal to the kernel bits, so a simple bitwise AND 
would be sufficient. Rewriting the series of conditionals into one expression 
allows GCC to optimize it:

    *cur_leds =
        (bios_state & BIOS_LED_SCR ? LED_SCR : 0) |
        (bios_state & BIOS_LED_NUM ? LED_NUM : 0) |
        (bios_state & BIOS_LED_CAP ? LED_CAP : 0);

Let me resend v2 of the patch,
Petr Tesarik