Re: VPD in sysfs

[Douglas Gilbert <dougg@torque.net>]

Matthew Wilcox wrote:
> I've been sent a patch that reads some VPD from the Symbios NVRAM and
> displays it in sysfs.  I'm not sure whether the way the author chose
> to present it is the best.  They put it in 0000:80:01.0/host0/vpd_name
> which seems a bit too scsi-specific and insufficiently forward-looking
> (I bet we want to expose more VPD data than that in the future, so we
> should probably use a directory).
> 
> I actually have a feeling (and please don't kill me for saying this), that
> we should add a struct vpd * to the struct device.  Then we need something
> like the drivers/base/power/sysfs.c file (probably drivers/base/vpd.c)
> that takes care of adding vpd to each device that wants it.
> 
> Thoughts?  Since there's at least four and probably more ways of getting
> at VPD, we either need to fill in some VPD structs at initialisation or
> have some kind of vpd_ops that a driver can fill in so the core can get
> at the data.

Vital Product Data (VPD) seems to be an ever increasing
area for all sorts of data. Here is a list (from sg_inq
in sg3_utils) of existing and proposed VPD pages for SCSI
targets and LUs:

struct vpd_name {
     int number;
     int peri_type;
     char * name;
};

static struct vpd_name vpd_name_arr[] = {
     {0x0, 0, "Supported VPD pages"},
     {0x80, 0, "Unit serial number"},
     {0x82, 0, "ASCII implemented operating definition"},
     {0x83, 0, "Device identification"},
     {0x84, 0, "Software interface identification"},
     {0x85, 0, "Management network addresses"},
     {0x86, 0, "Extended INQUIRY data"},
     {0x87, 0, "Mode page policy"},
     {0x88, 0, "SCSI ports"},
     {0x89, 0, "ATA information"},
     {0xb0, 0, "Block limits (sbc2)"},
     {0xb0, 0x1, "SSC device capabilities (ssc3)"},
     {0xb0, 0x11, "OSD information (osd)"},
     {0xb1, 0x11, "Security token (osd)"},
};

The most interesting one in the above list is the
"Device identification" VPD page (0x83) which may contain
multiple descriptors each identifying either a:
   - SCSI port (of a target)
   - SCSI target
   - SCSI logical unit

And here is a selection of possible identifier formats:
    - naa (2,5 or 6)
    - eui-64
    - t10 vendor
    - SCSI name string (iSCSI here)
    - MD5 logical unit identifier
    - vendor specific
amongst others.

["The great thing about standards is that there are so many
to choose from."]

And your patch is about attaching VPD data to a SCSI HBA (host)
via sysfs.
"struct vpd" should be interesting ...

Doug Gilbert