[coreboot] [PATCH]Move QRANK_DIMM_SUPPORT to Kconfig

[Scott Duplichan]

-----Original Message-----
From: Ward Vandewege [mailto:ward at gnu.org] 
Sent: Friday, November 05, 2010 01:42 PM
To: Scott Duplichan
Cc: 'Peter Stuge'; coreboot at coreboot.org
Subject: Re: [coreboot] [PATCH]Move QRANK_DIMM_SUPPORT to Kconfig

]On Fri, Nov 05, 2010 at 01:28:59PM -0500, Scott Duplichan wrote:
]> I am no quad rank dimm expert, but I think few boards support them. One is Serengeti
]> Cheetah. I remember asking why one processor socket has 4 dimm slots and another 8.
]> I was told it was for quad rank dimm testing. The chip selects for two normal dimm sockets
]> are combined and routed to a quad rank socket, if I remember correctly. I don't even
]> have any quad ranked dimms to test with. I think they are rare.
]
]Actually, they are not *that* rare, since they are readily available:
]
]  ]http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&DEPA=0&Order=BESTMATCH&Description=ddr3]+quad+rank&x=0&y=0

Sure enough. And not a bad price (per MB), either. Thanks for pointing them out.

Though I would question the maturity of coreboot support for registered
DDR3 in general, and specifically for 1333 speed or quad rank. I believe
these were perfected internally at AMD only recently. How well has coreboot
been tested with various speeds of registered DDR3? There is a lot more
complexity in the memory init code when registered DIMMs of any rank count
are used. And there is still the question of what boards supported by coreboot
really have hardware support for quadrank. I would hate to mislead someone
into buying a system loaded with registered memory with the idea of running
coreboot, unless it is known to work.

Thanks,
Scott

]-- 
]Ward Vandewege <ward at fsf.org>
]Free Software Foundation - Senior Systems Administrator