From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mikulas Patocka Subject: Re: [GIT PULL] parisc huge page support for v4.4 Date: Tue, 24 Nov 2015 11:39:51 -0500 (EST) Message-ID: References: <20151122115153.GA28471@p100.box> <5654892D.1030707@gmx.de> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Linus Torvalds , linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, James Bottomley , John David Anglin To: Helge Deller Return-path: In-Reply-To: <5654892D.1030707@gmx.de> List-ID: List-Id: linux-parisc.vger.kernel.org On Tue, 24 Nov 2015, Helge Deller wrote: > > Hi > > > > Since the kernel 4.4-rc2 I'm getting frequent boot failures on PA-RISC. > > When I revert this patchset, the crashes are gone. > > > [ 3.296666] CPU(s): 4 out of 4 PA8900 (Shortfin) at 1000.000000 MHz online > > Hi Mikulas, > > Yes, I've seen this as well. > It affects only the PA8900 CPUs, while all PA8500-PA8700 machines seem to work fine. > I do have a temporary 3-line patch to avoid the crashes which I'll push to my tree shortly. > I'm still investigating why it only affects the PA8900 CPUs, but I assume > it's related to the cache aliasing of those CPUs. > I'll keep you updated. > > Helge The PA-RISC specification doesn't allow aliasing on non-equaivalent addresses. Can the kernel map a piece of kernel data to other virtual address? If yes, we can't use big pages to map kernel data. Mikulas