Reserving large amounts of RAM for busmastering PCI card.

From: John P. Hartmann (
Date: Wed Jul 25 2001 - 08:23:43 EST

 RE: Reserving large amounts of RAM for busmastering PCI card.

 Please CC on your replies.

 I have an IBM P390 card, which will use up to 512M of contiguous
 RAM for "expanded storage", which can be thought of as a swap device.

 On the 2.2 kernels I modified setup.c to parse RESERVE=nnnM and take
 that amount off the top of the bios-reported memory size. My module
 then picks the address and size up from a place where I left them at
 boot time.

 Since the 2.4 kernels introduce the e820map structure, I'd like to
 plug into that infrastructure, and create a new type memory segment
 for this storage (I envisage having more than one segment), but in the
 2.4.4 kernel (which I am forced to remain with for quite a while) it
 seems not to be used apart from set up at boot time.

 I'm quite happy to do the work to generalise this, if I could get a
 pointer as to the direction that is envisaged.


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