From mboxrd@z Thu Jan 1 00:00:00 1970 From: Russell King Date: Sat, 24 May 2003 07:38:07 +0000 Subject: [Linux-ia64] Re: /proc/kcore - how to fix it Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org On Fri, May 23, 2003 at 04:51:43PM -0700, Luck, Tony wrote: > > One alternative I considered was to use just do a page table lookup. > > But I fear that some architectures use direct mapping registers etc. > > with mappings not in the page tables for the direct mapping, so it > > probably won't work for everybody. > > You are right. IA64 maps the kernel with some locked registers, so > there are no pagetables to show that the mapping exists. ARM maps the kernel direct-mapped RAM using 1MB section mappings, which the normal pgd/pmd/pte macros don't recognise as being valid. > I don't know ... you'll have to dust off those fixes for /proc to let > the negative file offsets get as far as the kcore.c code so we can > see what utilities work. In practice we probably don't care about > anything other than gdb. gdb definitely breaks - that's why I had to do the changes in the first place. gdb tries to lseek to negative 64-bit file offsets, which the kernel rejects with EINVAL iirc. (Tried it earlier this week.) -- Russell King (rmk@arm.linux.org.uk) The developer of ARM Linux http://www.arm.linux.org.uk/personal/aboutme.html