Re: physical memory access

Alan Cox (alan@lxorguk.ukuu.org.uk)
Thu, 4 Mar 1999 16:33:51 +0000 (GMT)

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> Physical memory is 1:1 mapped at PAGE_OFFSET (normally 0xc000000 on the
> x86). Just add PAGE_OFFSET to the address you really want to read.

Not all of memory is mapped this way. The main system ram and ISA space are.
PCI and other "high" memory area devices on a PC you need to use ioremap
to map them into the kernel space.

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