From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 28 Aug 2000 16:12:52 +0100 From: "Stephen C. Tweedie" Subject: Re: How does the kernel map physical to virtual addresses? Message-ID: <20000828161252.C1467@redhat.com> References: <20000825233748Z130198-15329+2857@vger.kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: ; from tigran@veritas.com on Mon, Aug 28, 2000 at 01:56:34PM +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: Tigran Aivazian Cc: Timur Tabi , Linux MM mailing list , Linux Kernel Mailing list List-ID: Hi, On Mon, Aug 28, 2000 at 01:56:34PM +0100, Tigran Aivazian wrote: > > it is interesting to observe that many questions that deal with _details_ > are answered quickly but questions related to fundamental concepts related > to how Linux is designed, baffle all of us (since 0 people answered). So, > is there really nobody in the whole world who can answer this? I would > like to know the answer (about global kernel memory layout - i.e. what > goes into PSE pages and what goes into normal ones, and how does PAE mode > change the picture?) myself... If PSE is available, it is used to map the bits of the kernel's VA which permanently maps all of physical memory. As a result, those pages cannot necessarily be looked up via a normal page table walk. Anything dynamically mapped --- ie. high pages (if using PAE), or vmalloc/ioremap pages --- is mapped using normal 4k ptes. mem_map[] is completely unaffected by the use of PSE, and continues to keep one entry per 4k physical page regardless of how the page tables have been constructed. --Stephen -- 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/