From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 24 Jan 2001 14:48:05 -0600 From: Timur Tabi In-Reply-To: <3A6F3E05.4090409@valinux.com> References: <20010124174824Z129401-18594+948@vger.kernel.org> <20010124203012Z129444-18594+1042@vger.kernel.org> Subject: Re: Page Attribute Table (PAT) support? Message-Id: <20010124204518Z131205-223+50@kanga.kvack.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Linux Kernel Mailing list Cc: Linux MM mailing list List-ID: ** Reply to message from Jeff Hartmann on Wed, 24 Jan 2001 13:41:41 -0700 > When you mark a page UCWC, you better > have removed all cached mappings or your asking for REAL trouble. What exactly do you mean by "removed all cached mappings"? Does that mean that if one virtual address is a UCWC mapping of a physical page, then ALL virtual addresses mapped to that page must also be UCWC? In my driver, I use ioremap_nocache() on physical memory (real RAM) to create an uncached "alias" (a virtual address) to a physical page of RAM. When I access the memory via this virtual address, the memory access is not cached. What I reall need is to be able to also have that virtual address as Write Combined. Since all physical RAM is mapped as cached via the kernel (on a 1-to-1 basis), and since there can be several other virtual addresses that point to that memory (e.g. user virtual address), I can't see how these virtual addresses can be removed. -- Timur Tabi - ttabi@interactivesi.com Interactive Silicon - http://www.interactivesi.com When replying to a mailing-list message, please direct the reply to the mailing list only. Don't send another copy to me. -- 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/