From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by oss.sgi.com (8.11.2/8.11.3) id g08NLok04648 for linux-mips-outgoing; Tue, 8 Jan 2002 15:21:50 -0800 Received: from dea.linux-mips.net (localhost [127.0.0.1]) by oss.sgi.com (8.11.2/8.11.3) with ESMTP id g08NLkg04645 for ; Tue, 8 Jan 2002 15:21:46 -0800 Received: (from ralf@localhost) by dea.linux-mips.net (8.11.1/8.11.1) id g08MLJ722305; Tue, 8 Jan 2002 20:21:19 -0200 Date: Tue, 8 Jan 2002 20:21:19 -0200 From: Ralf Baechle To: Kevin Paul Herbert Cc: linux-mips@oss.sgi.com Subject: Re: Support for physical memory above 0x20000000 Message-ID: <20020108202119.B21992@dea.linux-mips.net> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5i In-Reply-To: ; from kph@ayrnetworks.com on Tue, Jan 08, 2002 at 11:07:53AM -0800 X-Accept-Language: de,en,fr Sender: owner-linux-mips@oss.sgi.com Precedence: bulk On Tue, Jan 08, 2002 at 11:07:53AM -0800, Kevin Paul Herbert wrote: > I'm working with a somewhat dated kernel (2.4.2+patches) and have > discovered that there are problems with physical memory that does not > map into KSEG0/KSEG1. I looked over the list archives (manually, I > couldn't find a search interface) and it appears that this is still > the case for current kernels (at least as of a note from last summer, > the last time the issue seems to have come up.) > > Obviously, phys_to_virt() is going to be a problem but besides this > I'm wondering what anybody may have done to support physical memory > that is not always mapped into the virtual address space, so that I > don't have to reinvent the wheel. > > When I tell the kernel about the memory above 0x20000000, userland > fails to start; the kernel gets as far as execve()'ing init, but > nothing happens (interrupts are enabled; I get echo on the console, > but nothing from userland). Correct. There are two ways to solve this problem. For the 32-bit kernel I've got a highmem patch and the 64-bit kernel memory limits are the hardware's memory limits. I'll post the highmem patch soon. I was planning to have it ready by now but a flu sent me to bed instead ... Ralf