On 6/9/05, Christopher SEKIYA <wileyc@rezrov.net> wrote:
> On Thu, Jun 09, 2005 at 08:19:25PM +1000, Max Matveev wrote:
>=20
> > When why is ChalS in IP22 class - it's the same board as Indy.
>=20
> If the board sets bit 0 in IOC_SYSID, it is an IP24 ("Guiness").  If the =
bit
> is not set, it is an IP22.
>=20
> The Challenge S might use a chopped-down IP24 board -- if such were the
> case, one would expect that bit to be set.  However, SGI design engineers=
 have
> been known to make interesting hardware design decisions.
>=20
> (disclaimer: I've never seen the inside of a Challenge S, and I've never
> seen the dmesg from a Challenge S)
>=20
> The IP22/IP24 hardware docs make a distinction between IP22/IP24, there a=
re
> numerous minor register-level differences between the two, so we continue=
 the
> differentiation.
>=20
> > Actually, IP24 and IP26 never have being used for product names, they
> > were for internal use only.
>=20
> That's nice.  Every hardware reference that I've seen, SGI or otherwise,
> lists IP24 as a valid ID.  Google a bit for "SGI IP24", or read the IOC
> documentation.
>=20
> Your headers indicate that you work at/for SGI Australia.  For concrete r=
easons
> why SGI decided to use IP24 as a designation for the Indy rather than IP2=
2,
> I suggest that you ask your counterparts in Mountain View.
>=20
> -- Chris
>=20

Oh come now, everyone.  Nearly all who worked on Indy / Challenge S
are long gone from
SGI.  IP22 at the 'hinv' level is either an Indigo2, Indy, or
Challenge S.  While Indy / Challenge S are essentially the same
hardware, they're rather different than an I2.

Early releases of the Challenge S were straightforward Indy motherboards
with the dual SCSI + ethernet daughterboard in place of the graphics
daughterboard.
Once production ramped up, all Indy specific bits were pulled off the
mobo (sound, vino, perhaps ISDN) to save costs.

I'd expect IP24 to be the actual 'guiness' style mobo, which could
hold R4000, R4400, R5000, and some other R5k flavor of CPU, vs the
Indigo2 IP22, which AFAIK could never hold an R5k, just R4k (IP22),
R8k (IP26), or R10k (IP28).

Hope this helps,

--Chan
 (also at SGI, FWIW)