On 8/3/05, Mark Bellon <[EMAIL PROTECTED]> wrote: > Bartlomiej Zolnierkiewicz wrote: > > >On 8/3/05, Mark Bellon <[EMAIL PROTECTED]> wrote: > > > > > >>Bartlomiej Zolnierkiewicz wrote: > >> > >> > >> > >>>Hi, > >>> > >>>The topic was discussed to death on linux-kernel. > >>> > >>>Mark, you need to fix your applications and stop using > >>>/proc/ide/hd*/geometry > >>>or/and HDIO_GET_GEO ioctl (which BTW your patch also affects). > >>> > >>> > >>> > >>> > >>Fixing the applications I can understand but the patch still seems > >>necessary, to me, so the > >>HDIO_GET_GEO returns "rational" values. > >> > >>I tested HDIO_GET_GEO and it returns the same broken values as go into > >>/proc (no surprises) without my patch. > >> > >> > > > >Please explain. > > > > > Let me explain more below. Thanks for the response as now I can > understand better the issue (which was what I was fishing for). > > > > > > >>If a drive is in LBA mode (28 or 48 bit) the existing code doesn't > >>always "fix up" the geometry properly for some value returns. It only > >>tries with 48 bit mode and it fails there for some values. My patch > >>forces a complete geometry and appears (to me) to preserve the side > >>efefcts of the existing code. > >> > >>Am I missing something? > >> > >> > > > >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) { > > > >why are you forcing drive->bios_sect and drive->bios_head values for LBA28 > >drives? > > > > > Any LBA 28 drive can return fixed geometry (regardless of size) just as > well as an LBA 48 drive can. I've got drives all over the place that do > just that. In any event there are machines which do not have have an > BIOS, like a PPC target, and the BIOS values can be "fixed up". > > The ioctl returns the BIOS values and these are totally wrong on some > targets. Comments?
Simple: do not use BIOS values. [ Yes, there should be some warning from kernel. ] > >+ drive->bios_sect = drive->sect = 63; > >+ drive->bios_head = drive->head = 255; > > t> >changing drive->sect and drive->head is just wrong, > >these are values reported by the device - do not touch them > > > > > If drive->cyl, drive-head amd drive->sect are to be left alone in all > cases I have no problem. > > >+ > >+ cylsz = drive->bios_sect * drive->bios_head; > >+ cyl = do_div64_32(capacity, cylsz); > > > >division by zero now is possible (yes, 0/0/0 is possible) > > > > > Then the original code is prefered. > > >+ > >+ /* "fake out" works up to ~500 GB */ > >+ cyl = (cyl > 65535) ? 65535 : cyl; > >+ drive->bios_cyl = drive->cyl = cyl; > > > >drive->cyl shouldn't be changed > > > > > Same comment as above. Only change BIOS values. > > > } > > > > 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; > > > >cap0 != capacity => set the max possible drive->bios_cyl, > >no need for adjusting it > > > >- else { > > > >cap0 == capacity => no need for do_div(), only lower 32-bits are used, > >adjust drive->bios_cyl > > > >- 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)", > > > > > I understand clearly now... > > mark > > > > > > >>mark > >> > >> > >> > >>>Bartlomiej > >>> > >>>On 8/3/05, Andre Hedrick <[EMAIL PROTECTED]> wrote: > >>> > >>> > >>> > >>> > >>>>Did you read ATA-1 through ATA-7 to understand all the variations? > >>>> > >>>>On Tue, 2 Aug 2005, Mark Bellon wrote: > >>>> > >>>> > >>>> > >>>> > >>>> > >>>>>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 <[EMAIL PROTECTED]> > >>>>> > >>>>> > > - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/