From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 9 Dec 2004 10:36:44 -0800 From: William Lee Irwin III Subject: Re: Fwd: Re: Plzz help me regarding HIGHMEM (PAE) confusion in Linux-2.4 ??? Message-ID: <20041209183644.GB2714@holomorphy.com> References: <20041209125425.85749.qmail@web53901.mail.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20041209125425.85749.qmail@web53901.mail.yahoo.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Fawad Lateef Cc: linux-mm@kvack.org List-ID: On Thu, Dec 09, 2004 at 04:54:25AM -0800, Fawad Lateef wrote: > but what I saw is that the pgd is loaded in cr3 when > the switch_mm takes place in the scheduling of > process. And PGD is of 64bit size ................ can > u please explain this ??? The pgd is not loaded into %cr3, only its address. On Thu, Dec 09, 2004 at 04:54:25AM -0800, Fawad Lateef wrote: > Actually I m concerned in accessing 4GB to 32GB for > ramdisk, and when I used to access those through > kmap_atomic in a single module system crashes after > passing the first 4GB of RAM (screen shows garbage and > then system crashes), I got to know that a process can > only access 4GB, so I created kernel threads for each > 4GB and allocated struct mm_struct entry to that > through mm_alloc function and then assigned that to > the task_struct->active_mm to each thread, (in thread > before mm_alloc I called daemonize too)......... > Now I think that all threads are now different > processes, but the system crashing behaviour is the > same ............. kernel is 2.4.25 > Can u plz suggest me some way of doing this ??? There is only one kernel address space. You are probably actually trying to write blkdev-highmem, but it would be far easier to populate a ramfs at boot instead of using a ramdisk. The ramdisk block driver is crusty and probably qualifies as broken on 32-bit due to the resource scalability issues. It would be much easier (and you'd encounter much less negative feedback) using ramfs or a 64-bit architecture. -- wli -- 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/ . Don't email: aart@kvack.org