Re: Kernel memory limits?

From: Coywolf Qi Hunt
Date: Thu Mar 17 2005 - 15:18:43 EST


linux-os wrote:
On Thu, 17 Mar 2005, Peter W. Morreale wrote:

(I did not see this addressed in the FAQs...)

How much physical memory can the 2.4.26 kernel address in kernel context on x86?


All of it.

What about DMA memory?


All of it, too. The old DMA controller(s) could only address 16 MB
because that's all the page-registers allowed. Bus-mastering DMA
off the PCI/Bus has no such limitation. Most have DMA controllers
that use scatter-lists so RAM doesn't even have to be contiguous,
only properly allocated (in pages) and nailed down with no caching.


Kernel Image itself resides at physical address 1M. Is this kernel image
area a hole to the old DMA range? Thanks.


Coywolf


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