From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 1 May 2001 13:09:52 -0400 (EDT) From: Alexander Viro Subject: Re: About reading /proc/*/mem In-Reply-To: <3AEEEA09.7000301@link.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Richard F Weber Cc: "Eric W. Biederman" , linux-mm@kvack.org List-ID: On Tue, 1 May 2001, Richard F Weber wrote: > See this is where I start seeming to have problems. I can open > /proc/*/mem & lseek, but reads come back as "No such process". However, > if I first do a ptrace(PTRACE_ATTACH), then I can read the data, but the > process stops. I've kind of dug through the sys_ptrace() code under > /usr/src/linux/arch/i386/kernel/ptrace.c, and can see and understand > generally what it's doing, but that's getting into serious kernel-land > stuff. I wouldn't expect it to be this difficult to just open up > another processes /proc/*/mem file to read data from. > Is there something obvious I'm missing? It seems to keep pointing back > to ptrace & /proc/*/mem are very closely related (ie: the same) > including stopping of the child. OK, here's something I really don't understand. Suppose that I tell your debugger to tell me when in the executed program foo becomes greater than bar[0] + 14. Or when cyclic list foo becomes longer than 1 element (i.e. foo.next != foo.prev). How do you do that if program is running? If you don't guarantee that it doesn't run during the access to its memory (moreover, between sever such accesses) - the data you get is worthless. -- 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/