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Conference smurf::ase

Title:	ase

Moderator:	SMURF::GROSSO

Created:	Thu Jul 29 1993
Last Modified:	Fri Jun 06 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	2114
Total number of notes:	7347

2057.0. "memory channel" by CUESTA::VEIGA () Wed May 14 1997 03:06

    Hi:
    
    Perhaps this can be a naive question.
    In all books about memory channel functionality said literaly:
    "Cluster member systems communicate over the MC via write-only
    transactions.The systems reserve from 128 to 512Mbytes of pci I/O bus
    address space for transmitting data to the pci Mc adapter,and a
    separate 128 to 512Mbytes of bus address space for receiving data"
    
    My questions is:
    
    Is there any piece of physical memory reserved ONLY for MEMORY CHANNEL
    transactions?
    Thank you
    
    Txemi

T.R	Title	User	Personal Name	Date	Lines
2057.1		COMICS::CORNEJ	What's an Architect?	`Wed May 14 1997 05:44`	6
	Well, there is no physical memory in the MC hardware (buffers aside), so it must be physical memory in the hosts. It is not a block of "shared memory" as such though. Jc
2057.2	Correct.	NNTPD::"[email protected]"	Dave Cherkus	`Wed May 14 1997 10:13`	9
	Every host creates a 128 MB transmit region in PCI space. The receive memory comes from the host. It is only allocated as needed, so there is no waste of memory. The dma scatter gather table is programmed with the proper information so that data written from the memory channel ends up in the right page of physical memory. Dave [Posted by WWW Notes gateway]