From mboxrd@z Thu Jan 1 00:00:00 1970 From: "ZCane, Ed (Test Purposes)" Message-ID: <00c701c32f70$4b13b050$d8c176c1@roke.co.uk> References: <20030610004512.6358fdfb.akpm@digeo.com> Subject: Problem with bootmem/mmap Date: Tue, 10 Jun 2003 17:49:43 +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: Dear all, I'm allocating a large buffer at boot time (for later DMA purposes) using: buf=alloc_bootmem_low_pages(1024*1024*500); If I printk here, from init/main.c, I get: buf=0xc1e14000 __va(buf)=0x81e14000 __pa(buf)=0x1e14000 Now, in user-space, I'm trying to get access to my buffer (as root), by doing the following: memfd=open("/dev/mem", O_RDWR); my_buf=mmap(0, 1024*1024*501, PROT_READ|PROT_WRITE, MAP_SHARED|MAP_FIXED, memfd, OFFSET); I've tried all those addresses above, as the OFFSET, but it either generates an illegal instruction, or a segfault. Bit of a beginner, but learning fast, and I'd be _really_ greatful, if anyone could help me! Many thanks, Ed begin 666 RMRL-Disclaimer.txt M4F5G:7-T97)E9"!/9F9I8V4Z(%)O:V4@36%N;W(@4F5S96%R8V@@3'1D+"!3 M:65M96YS($AO=7-E+"!/;&1B=7)Y+"!"2!W:71H;W5T('!E aart@kvack.org