From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 5 Jun 2001 16:42:52 -0400 From: cohutta Subject: Re: temp. mem mappings Message-ID: <3B581215@MailAndNews.com> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org List-ID: > > > Allocate a virtual memory area using vmalloc and then save and modify the > > > pmd/pgd/pte to point to the physical memory you want. To unmap, just undo the > > > previous steps. > > > > ioremap() is there for exactly that purpose. > > True, except that you can't use ioremap on normal memory, which is what I > assumed he was trying to do. Normal memory is identity-mapped very early in boot anyway (except for highmem on large Intel boxes, that is, and kmap() works for that.) --- I don't really want to play with the page tables if i can help it. I didn't use ioremap() because it's real system memory, not IO bus memory. How much normal memory is identity-mapped at boot on x86? Is it more than 8 MB? I'm trying to read some ACPI tables, like the FACP. On my system, this is at physical address 0x3fffd7d7 (e.g.). kmap() ends up calling set_pte(), which is close to what i am already doing. i'm having a problem on the unmap side when i am done with the temporary mapping. thanks. /cohutta/ -- 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-mm.org/