From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 25 Jan 2001 11:11:04 -0600 From: Timur Tabi In-Reply-To: <3A705CAF.70909@valinux.com> References: <3A6D5D28.C132D416@sangate.com> <20010123165117Z131182-221+34@kanga.kvack.org> <20010123165117Z131182-221+34@kanga.kvack.org> ; from ttabi@interactivesi.com on Tue, Jan 23, 2001 at 10:53:51AM -0600 <20010125155345Z131181-221+38@kanga.kvack.org> <20010125165001Z132264-460+11@vger.kernel.org> Subject: Re: ioremap_nocache problem? Message-Id: <20010125170824Z131181-224+39@kanga.kvack.org> Sender: owner-linux-mm@kvack.org Return-Path: To: Jeff Hartmann Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: ** Reply to message from Jeff Hartmann on Thu, 25 Jan 2001 10:04:47 -0700 > > The problem with this is that between the ioremap and iounmap, the page is > > reserved. What happens if that page belongs to some disk buffer or user > > process, and some other process tries to free it. Won't that cause a problem? > > The page can't belong to some other process/kernel component. You own > the page if you allocated it. Ok, my mistake. I wasn't paying attention to the "get_free_pages" call. My problem is that I'm ioremap'ing someone else's page, but my hardware sits on the memory bus disguised as real memory, and so I need to poke around the 4GB space trying to find it. > (I was the one who added support to > the kernel to ioremap real ram, trust me.) I really appreciate that feature, because it helps me a lot. Any recommendations on how I can do what I do without causing any problems? Right now, my driver never calls iounmap on memory that's in real RAM, even when it exits. Fortunately, the driver isn't supposed to exit, so all it does is waste a few KB of virtual memory. -- 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/