Messages in this thread Patch in this message | | | Date | Tue, 02 Aug 2005 14:27:35 -0700 | From | Mark Bellon <> | Subject | [PATCH] IDE disks show invalid geometries in /proc/ide/hd*/geometry |
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The ATA specification tells large disk drives to return C/H/S data of 16383/16/63 regardless of their actual size (other variations on this return include 15 heads and/or 4092 cylinders). Unfortunately these CHS data confuse the existing IDE code and cause it to report invalid geometries in /proc when the disk runs in LBA mode.
The invalid geometries can cause failures in the partitioning tools; partitioning may be impossible or illogical size limitations occur. This also leads to various forms of human confusion.
I attach a patch that fixes this problem while strongly attempting to not break any existing side effects and await any comments.
mark
Signed-off-by: Mark Bellon <mbellon@mvista.com>
diff -Naur linux-2.6.13-rc3-git9-orig/drivers/ide/ide-disk.c linux-2.6.13-rc3-git9/drivers/ide/ide-disk.c --- linux-2.6.13-rc3-git9-orig/drivers/ide/ide-disk.c 2005-08-01 13:48:21.000000000 -0700 +++ linux-2.6.13-rc3-git9/drivers/ide/ide-disk.c 2005-08-02 12:14:43.000000000 -0700 @@ -884,10 +884,17 @@ ide_add_setting(drive, "max_failures", SETTING_RW, -1, -1, TYPE_INT, 0, 65535, 1, 1, &drive->max_failures, NULL); } +static uint32_t do_div64_32 (__u64 n, uint32_t d) +{ + do_div(n, d); + + return n; +} + static void idedisk_setup (ide_drive_t *drive) { struct hd_driveid *id = drive->id; - unsigned long long capacity; + __u64 capacity; int barrier; idedisk_add_settings(drive); @@ -949,27 +956,32 @@ */ capacity = idedisk_capacity (drive); if (!drive->forced_geom) { + uint32_t cylsz, cyl; - if (idedisk_supports_lba48(drive->id)) { - /* compatibility */ - drive->bios_sect = 63; - drive->bios_head = 255; + /* + * In LBA mode the geometry isn't used to talk to the drive + * so always create a "rational" geometry from the capacity. + */ + if (drive->select.b.lba) { + drive->bios_sect = drive->sect = 63; + drive->bios_head = drive->head = 255; + + cylsz = drive->bios_sect * drive->bios_head; + cyl = do_div64_32(capacity, cylsz); + + /* "fake out" works up to ~500 GB */ + cyl = (cyl > 65535) ? 65535 : cyl; + drive->bios_cyl = drive->cyl = cyl; } if (drive->bios_sect && drive->bios_head) { - unsigned int cap0 = capacity; /* truncate to 32 bits */ - unsigned int cylsz, cyl; + cylsz = drive->bios_sect * drive->bios_head; + cyl = do_div64_32(capacity, cylsz); - if (cap0 != capacity) - drive->bios_cyl = 65535; - else { - cylsz = drive->bios_sect * drive->bios_head; - cyl = cap0 / cylsz; - if (cyl > 65535) - cyl = 65535; - if (cyl > drive->bios_cyl) - drive->bios_cyl = cyl; - } + if (cyl > 65535) + cyl = 65535; + if (cyl > drive->bios_cyl) + drive->bios_cyl = cyl; } } printk(KERN_INFO "%s: %llu sectors (%llu MB)", | |