Revert "x86: fix ghost EDD devices in /sys again"

[linux-2.6-omap-h63xx.git] / arch / x86 / boot / edd.c

diff --git a/arch/x86/boot/edd.c b/arch/x86/boot/edd.c
index d84a48ece78503b10e8429981e44397b6755a454..1aae8f3e5ca1912b6eb60ad75e3c120af1110bed 100644 (file)
--- a/arch/x86/boot/edd.c
+++ b/arch/x86/boot/edd.c
@@ -41,6 +41,7 @@ static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
        char *mbrbuf_ptr, *mbrbuf_end;
        u32 buf_base, mbr_base;
        extern char _end[];
+       u16 mbr_magic;
 
        sector_size = ei->params.bytes_per_sector;
        if (!sector_size)
@@ -58,11 +59,15 @@ static u32 read_mbr_sig(u8 devno, struct edd_info *ei, u32 *mbrsig)
        if (mbrbuf_end > (char *)(size_t)boot_params.hdr.heap_end_ptr)
                return -1;
 
+       memset(mbrbuf_ptr, 0, sector_size);
        if (read_mbr(devno, mbrbuf_ptr))
                return -1;
 
        *mbrsig = *(u32 *)&mbrbuf_ptr[EDD_MBR_SIG_OFFSET];
-       return 0;
+       mbr_magic = *(u16 *)&mbrbuf_ptr[510];
+
+       /* check for valid MBR magic */
+       return mbr_magic == 0xAA55 ? 0 : -1;
 }
 
 static int get_edd_info(u8 devno, struct edd_info *ei)
@@ -126,17 +131,25 @@ void query_edd(void)
 {
        char eddarg[8];
        int do_mbr = 1;
+#ifdef CONFIG_EDD_OFF
+       int do_edd = 0;
+#else
        int do_edd = 1;
+#endif
        int be_quiet;
        int devno;
        struct edd_info ei, *edp;
        u32 *mbrptr;
 
        if (cmdline_find_option("edd", eddarg, sizeof eddarg) > 0) {
-               if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip"))
+               if (!strcmp(eddarg, "skipmbr") || !strcmp(eddarg, "skip")) {
+                       do_edd = 1;
                        do_mbr = 0;
+               }
                else if (!strcmp(eddarg, "off"))
                        do_edd = 0;
+               else if (!strcmp(eddarg, "on"))
+                       do_edd = 1;
        }
 
        be_quiet = cmdline_find_option_bool("quiet");
@@ -159,9 +172,8 @@ void query_edd(void)
                 * Scan the BIOS-supported hard disks and query EDD
                 * information...
                 */
-               get_edd_info(devno, &ei);
-
-               if (boot_params.eddbuf_entries < EDDMAXNR) {
+               if (!get_edd_info(devno, &ei)
+                   && boot_params.eddbuf_entries < EDDMAXNR) {
                        memcpy(edp, &ei, sizeof ei);
                        edp++;
                        boot_params.eddbuf_entries++;