From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <20010220153722.51795.qmail@web12702.mail.yahoo.com> Date: Tue, 20 Feb 2001 07:37:22 -0800 (PST) From: Alan Cudmore Subject: How to allocate large blocks of contiguous physical RAM? MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: owner-linux-mm@kvack.org Return-Path: To: Linux-MM@kvack.org List-ID: Hi, I'm trying to figure out how to allocate a large block of contiguous physical memory under linux 2.4.x. I have 4GB of RAM and have turned on the CONFIG_HIGMEM4G option. Previously I was using the "bigphysarea" patch, but that seems to have a limit of around 900MB. ( is that because it is being allocated from the 1Gig kernel physical memory ? ) Also, I have considered changing the PAGE_OFFSET define to 0x80000000 to give me a little under 2GB. Ideally I would like to do the following: 1. Pre-Allocate 2 or 3 gigs of contiguous memory 2. A custom PCI 64/66Mhz card will be DMAing data directly into this memory at very high rates ( up to 500MBytes per second, thus the need for a few gigs ) 3. Then I would like to be able to DMA data back out to SCSI without picking the data up ( using SCSI generic with Direct I/O ). I really am a linux-MM newbie, so I would appreciate advice on how I could accomplish such a feat, it it can be done at all. Any suggestions would be welcome. Thanks, Alan C. __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/ -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux.eu.org/Linux-MM/