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SubjectRe: [PATCH] Large "clipped" IDE disk support for 2.4 when using old BIOS
On Sun, 19 Nov 2000, Taisuke Yamada wrote:

> Earlier this month, I had sent in a patch to 2.2.18pre17 (with
> IDE-patch from http://www.linux-ide.org/ applied) to add support
> for IDE disk larger than 32GB, even if the disk required "clipping"
> to reduce apparent disk size due to BIOS limitation.
>
> [...] patch

This patch is not good. It compiles, but when I boot the kernel, it
decides to ignore the hdc=5606,255,63 parameter that I pass to the kernel,
and limits the number of sectors to fill 8.4GB.

(from dmesg:)

hdc: lba = 0, cap = 16514064
hdc: 16514064 sectors (8455 MB) w/1916KiB Cache, CHS=5606/255/63, UDMA(33)

Notes:
* Notice the contradiction between 16414064 sectors and 5606/255/63
geometry, something is definitly wrong there.
* I *didn't* change the jumper settings to 'clipping' mode, only the
kernel was modified in this test.
* When I try to read (using dd) from somewhere above the 40GB offset in
the drive, no success. I guess if I tried to read pass 8.4GB it
wouldn't have yield success either.
* In this test, the code in the patch doesn't printk() anything except
that 'hdc: lba = 0, cap = 16514064' line.
* Normally, without the patch I get:

hdc: 90069840 sectors (46116 MB) w/1916KiB Cache, CHS=5606/255/63,
UDMA(33)

And then there's no problem reading any offset on the drive.

* I really need this sort of patch, tired of booting the computer from a
floppy...
* The patch didn't want to apply for some reason, so I had to apply the
patch manually (to test11-pre7).

Here is the version of patch that does apply: (please release an
updated patch)

--- linux/drivers/ide/ide-disk.c Sun Nov 19 17:15:56 2000
+++ linux/drivers/ide/ide-disk.c Sun Nov 19 17:27:31 2000
@@ -513,24 +513,149 @@
current_capacity(drive));
}

+
+/*
+ * Tests if the drive supports Host Protected Area feature.
+ * Returns true if supported, false otherwise.
+ */
+static inline int idedisk_supports_host_protected_area(ide_drive_t *drive)
+{
+ int flag = (drive->id->command_set_1 & 0x0a) ? 1 : 0;
+ printk("%s: host protected area => %d\n", drive->name, flag);
+ return flag;
+}
+
+/*
+ * Queries for true maximum capacity of the drive.
+ * Returns maximum LBA address (> 0) of the drive, 0 if failed.
+ */
+static unsigned long idedisk_read_native_max_address(ide_drive_t *drive)
+{
+ byte args[7];
+ unsigned long addr = 0;
+
+ printk("%s: checking for max native LBA...\n", drive->name);
+
+ /* Create IDE/ATA command request structure
+ *
+ * NOTE: I'm not sure if I can safely use IDE_*_OFFSET macro
+ * here...For real ATA command structure, offset for IDE
+ * command is 7, but in IDE driver, it needs to be at 0th
+ * index (same goes for IDE status offset below). Hmm...
+ */
+ args[0] = 0xf8; /* READ_NATIVE_MAX - see ATA spec */
+ args[IDE_FEATURE_OFFSET] = 0x00;
+ args[IDE_NSECTOR_OFFSET] = 0x00;
+ args[IDE_SECTOR_OFFSET] = 0x00;
+ args[IDE_LCYL_OFFSET] = 0x00;
+ args[IDE_HCYL_OFFSET] = 0x00;
+ args[IDE_SELECT_OFFSET] = 0x40;
+
+ /* submit command request - if OK, read current max LBA value */
+ if (ide_wait_cmd_task(drive, args) == 0) {
+ if ((args[0] & 0x01) == 0) {
+ addr = ((args[IDE_SELECT_OFFSET] & 0x0f) << 24)
+ | ((args[IDE_HCYL_OFFSET] ) << 16)
+ | ((args[IDE_LCYL_OFFSET] ) << 8)
+ | ((args[IDE_SECTOR_OFFSET] ));
+ }
+ }
+
+ printk("%s: max native LBA is %lu\n", drive->name, addr);
+
+ return addr;
+}
+
+/*
+ * Sets maximum virtual LBA address of the drive.
+ * Returns new maximum virtual LBA address (> 0) or 0 on failure.
+ */
+static unsigned long idedisk_set_max_address(ide_drive_t *drive,
+ unsigned long addr_req)
+{
+ byte args[7];
+ unsigned long addr_set = 0;
+
+ printk("%s: (un)clipping max LBA...\n", drive->name);
+
+ /* Create IDE/ATA command request structure
+ *
+ * NOTE: I'm not sure if I can safely use IDE_*_OFFSET macro
+ * here...For real ATA command structure, offset for IDE
+ * command is 7, but in IDE driver, it needs to be at 0th
+ * index (same goes for IDE status offset below). Hmm...
+ */
+ args[0] = 0xf9; /* SET_MAX - see ATA spec */
+ args[IDE_FEATURE_OFFSET] = 0x00;
+ args[IDE_NSECTOR_OFFSET] = 0x00;
+ args[IDE_SECTOR_OFFSET] = ((addr_req ) & 0xff);
+ args[IDE_LCYL_OFFSET] = ((addr_req >> 8) & 0xff);
+ args[IDE_HCYL_OFFSET] = ((addr_req >> 16) & 0xff);
+ args[IDE_SELECT_OFFSET] = ((addr_req >> 24) & 0x0f) | 0x40;
+
+ /* submit command request - if OK, read new max LBA value */
+ if (ide_wait_cmd_task(drive, args) == 0) {
+ if ((args[0] & 0x01) == 0) {
+ addr_set = ((args[IDE_SELECT_OFFSET] & 0x0f) << 24)
+ | ((args[IDE_HCYL_OFFSET] ) << 16)
+ | ((args[IDE_LCYL_OFFSET] ) << 8)
+ | ((args[IDE_SECTOR_OFFSET] ));
+ }
+ }
+
+ printk("%s: max LBA (un)clipped to %lu\n", drive->name, addr_set);
+
+ return addr_set;
+}
+
/*
* Compute drive->capacity, the full capacity of the drive
* Called with drive->id != NULL.
+ *
+ * To compute capacity, this uses either of
+ *
+ * 1. CHS value set by user (whatever user sets will be trusted)
+ * 2. LBA value from target drive (require new ATA feature)
+ * 3. LBA value from system BIOS (new one is OK, old one may break)
+ * 4. CHS value from system BIOS (traditional style)
+ *
+ * in above order (i.e., if value of higher priority is available,
+ * rest of the values are ignored).
*/
static void init_idedisk_capacity (ide_drive_t *drive)
{
+ unsigned long hd_max;
+ unsigned long hd_cap = drive->cyl * drive->head * drive->sect;
+ int is_lba = 0;
+
struct hd_driveid *id = drive->id;
- unsigned long capacity = drive->cyl * drive->head * drive->sect;

- drive->select.b.lba = 0;
+ /* Unless geometry is given by user, use autodetected value */
+ if (! drive->forced_geom) {
+ /* If BIOS LBA geometry is available, use it */
+ if ((id->capability & 2) && lba_capacity_is_ok(id)) {
+ hd_cap = id->lba_capacity;
+ is_lba = 1;
+ }

- /* Determine capacity, and use LBA if the drive properly supports it */
- if ((id->capability & 2) && lba_capacity_is_ok(id)) {
- capacity = id->lba_capacity;
- drive->cyl = capacity / (drive->head * drive->sect);
- drive->select.b.lba = 1;
+ /* If new ATA feature is supported, try using it */
+ if (idedisk_supports_host_protected_area(drive)) {
+ hd_max = idedisk_read_native_max_address(drive);
+ hd_max = idedisk_set_max_address(drive, hd_max);
+
+ if (hd_max > 0) {
+ hd_cap = hd_max;
+ is_lba = 1;
+ }
+ }
}
- drive->capacity = capacity;
+
+ printk("%s: lba = %d, cap = %lu\n", drive->name, is_lba, hd_cap);
+
+ /* update parameters with fetched results */
+ drive->select.b.lba = is_lba;
+ drive->capacity = hd_cap;
+ drive->cyl = hd_cap / (drive->head * drive->sect);
}

static unsigned long idedisk_capacity (ide_drive_t *drive)

--
Dan Aloni
dax@karrde.org

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