diff options
| author | Ben Hutchings <ben@decadent.org.uk> | 2013-07-31 13:53:30 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-07-31 14:41:02 -0700 |
| commit | d39de28c95876f8becb559d242eefe718ea1f747 (patch) | |
| tree | c08bfae999e12bc54c0d3a577d439d7a27bf11a3 /drivers | |
| parent | 62c610460d73fcfa5637cb497c6923ef1c42b12d (diff) | |
dmi_scan: add comments on dmi_present() and the loop in dmi_scan_machine()
My previous refactoring in commit 79bae42d51a5 ("dmi_scan: refactor
dmi_scan_machine(), {smbios,dmi}_present()") resulted in slightly tricky
code (though I think it's more elegant). Explain what it's doing.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Cc: Zhenzhong Duan <zhenzhong.duan@oracle.com>
Cc: Jean Delvare <jdelvare@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/firmware/dmi_scan.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/firmware/dmi_scan.c b/drivers/firmware/dmi_scan.c index eb760a218da4..232fa8fce26a 100644 --- a/drivers/firmware/dmi_scan.c +++ b/drivers/firmware/dmi_scan.c @@ -419,6 +419,13 @@ static void __init dmi_format_ids(char *buf, size_t len) dmi_get_system_info(DMI_BIOS_DATE)); } +/* + * Check for DMI/SMBIOS headers in the system firmware image. Any + * SMBIOS header must start 16 bytes before the DMI header, so take a + * 32 byte buffer and check for DMI at offset 16 and SMBIOS at offset + * 0. If the DMI header is present, set dmi_ver accordingly (SMBIOS + * takes precedence) and return 0. Otherwise return 1. + */ static int __init dmi_present(const u8 *buf) { int smbios_ver; @@ -506,6 +513,13 @@ void __init dmi_scan_machine(void) if (p == NULL) goto error; + /* + * Iterate over all possible DMI header addresses q. + * Maintain the 32 bytes around q in buf. On the + * first iteration, substitute zero for the + * out-of-range bytes so there is no chance of falsely + * detecting an SMBIOS header. + */ memset(buf, 0, 16); for (q = p; q < p + 0x10000; q += 16) { memcpy_fromio(buf + 16, q, 16); |