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 
[EMAIL PROTECTED]

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