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efi: read microseconds from boot loader info instead of "ticks" magic

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This commit is contained in:
Kay Sievers 2013-01-23 02:16:11 +01:00
parent 780040dc2a
commit 5dbe9f5398
1 changed files with 4 additions and 58 deletions
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62
src/shared/efivars.c
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@ -93,45 +93,7 @@ int efi_get_variable(sd_id128_t vendor, const char *name, uint32_t *attribute, v
return 0;
}
static int read_bogomips(unsigned long *u) {
_cleanup_fclose_ FILE *f = NULL;
f = fopen("/proc/cpuinfo", "re");
if (!f)
return -errno;
while (!feof(f)) {
char line[LINE_MAX];
char *x;
unsigned long a, b;
if (!fgets(line, sizeof(line), f))
return -EIO;
char_array_0(line);
truncate_nl(line);
if (!startswith(line, "bogomips"))
continue;
x = line + 8;
x += strspn(x, WHITESPACE);
if (*x != ':')
continue;
x++;
x += strspn(x, WHITESPACE);
if (sscanf(x, "%lu.%lu", &a, &b) != 2)
continue;
*u = a * 1000000L + b * 10000L;
return 0;
}
return -EIO;
}
static int read_ticks(sd_id128_t vendor, const char *name, unsigned long speed, usec_t *u) {
static int read_usec(sd_id128_t vendor, const char *name, usec_t *u) {
_cleanup_free_ void *i = NULL;
_cleanup_free_ char *j = NULL;
size_t is;
@ -153,38 +115,22 @@ static int read_ticks(sd_id128_t vendor, const char *name, unsigned long speed,
if (r < 0)
return r;
*u = USEC_PER_SEC * x / speed;
*u = x;
return 0;
}
static int get_boot_usec(usec_t *firmware, usec_t *loader) {
uint64_t x, y;
int r;
unsigned long bogomips;
assert(firmware);
assert(loader);
/* Returns the usec after the CPU was turned on. The two
* timestamps are: the firmware finished, and the boot loader
* finished. */
/* We assume that the kernel's bogomips value is calibrated to
* twice the CPU frequency, and use this to convert the TSC
* ticks into usec. Of course, bogomips are only vaguely
* defined. If this breaks one day we can come up with
* something better. However, for now this saves us from doing
* a local calibration loop. */
r = read_bogomips(&bogomips);
r = read_usec(EFI_VENDOR_LOADER, "LoaderTimeInitUsec", &x);
if (r < 0)
return r;
r = read_ticks(EFI_VENDOR_LOADER, "LoaderTicksInit", bogomips / 2, &x);
if (r < 0)
return r;
r = read_ticks(EFI_VENDOR_LOADER, "LoaderTicksExec", bogomips / 2, &y);
r = read_usec(EFI_VENDOR_LOADER, "LoaderTimeExecUsec", &y);
if (r < 0)
return r;