From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sp1n294en1.watson.ibm.com (sp1n294en1.watson.ibm.com [9.2.112.58]) by igw3.watson.ibm.com (8.11.4/8.11.4) with ESMTP id fAKJn5O09682 for ; Tue, 20 Nov 2001 14:49:05 -0500 Received: from watson.ibm.com (discohall.watson.ibm.com [9.2.17.22]) by sp1n294en1.watson.ibm.com (8.11.4/8.11.4) with ESMTP id fAKJn5p28820 for ; Tue, 20 Nov 2001 14:49:05 -0500 Message-ID: <3BFAB48D.1A772321@watson.ibm.com> Date: Tue, 20 Nov 2001 14:52:45 -0500 From: "Raymond B. Jennings III" Reply-To: raymondj@watson.ibm.com MIME-Version: 1.0 Subject: help with highmem Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: linux-mm@kvack.org List-ID: I was wondering why if CONFIG_HIGHMEM is NOT turned on, the vmalloc area goes almost to the end of the 4GB boundary: VMALLOC_END = FIXADDR_START - 2*PAGE_SIZE - or - VMALLOC_END = (FIXADDR_TOP - FIXADDR_SIZE) - 2*PAGE_SIZE - or - (on my particular setup) VMALLOC_END = (FFFFE000h - 4*PAGE_SIZE) - 2*PAGE_SIZE In any case it is pretty close to the 4GB boundary BUT when you have CONFIG_HIGHMEM turned on: VMALLOC_END = PKMAP_BASE - 2*PAGE_SIZE I realize you need room for the pkmap_count array but the array only allows for 1024 pages. If PKMAP_BASE = FE000000h then this fills the address space upto FE400000. What is being used in the remaining section of the address space? Couldn't PKMAP_BASE be moved up (allow for a larger vmalloc area) or enlarge the pkmap_count array up to the point of VMALLOC_END as when CONFIG_HIGHMEM is turned off? Thanks for any help. -- 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/