Re: [PATCH] Large "clipped" IDE disk support for 2.4 when using old BIOS

[Andre Hedrick <andre@linux-ide.org>]

Taisuke,

After some changes in the code to conform to the near final taskfile
solution, it is called CONFIG_IDEDISK_STROKE.

It is in the latest patch for 2.2.17 published on kernel.org but I forgot
to remove a blocking stub in ide-disk.c

Please try it and comment offline for now.

Cheers,

On Sun, 19 Nov 2000, Taisuke Yamada wrote:

> 
> Hi.
> 
> 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.
> 
> BIOS known to have this limitation is Award 4.51 (and before) and
> it seems many mainboards with not-so-great vendor support still use it.
> 
> Now I'm moving to 2.4-based system, and so ported the patch to
> 2.4-test10. It also applies cleanly to 2.4-test11.
> 
> With this patch, you will be able to use disk capacity above
> 32GB (or 2GB/8GB depending on how clipping take effect), and
> still be able to boot off from the disk because you can leave
> the "clipping" turned on.
> 
> >From my experience, this patch works with both software and
> hardware clipping (or jumpering). This is probably because
> hardware jumper works as a flag to the disk to enable software
> clipping on hardware reset. But I'm not sure if this applies to
> all disks.
> 
> By the way, is it safe for me to use IDE_*_OFFSET macro as a index
> for IDE task command buffer? I couldn't use IDE_COMMAND_OFFSET (== 7),
> and had to specify 0 because that's what ide_cmd function requires.
> 
> Anyway, here's the patch. Hope it works well on other systems...
> 
> --- cut here --- cut here --- cut here --- cut here --- cut here ---
> --- linux/drivers/ide/ide-disk.c.orig    Sun Nov 19 03:17:57 2000
> +++ linux/drivers/ide/ide-disk.c    Sun Nov 19 03:22:43 2000
> @@ -514,23 +514,147 @@
>  }
>  
>  /*
> + * 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)
> --- cut here --- cut here --- cut here --- cut here --- cut here ---
> 
> --
> Taisuke Yamada <tai@imasy.or.jp>
> PGP fingerprint = 6B 57 1B ED 65 4C 7D AE  57 1B 49 A7 F7 C8 23 46
> -
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> 

Andre Hedrick
CTO Timpanogas Research Group
EVP Linux Development, TRG
Linux ATA Development

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