Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161084Ab2KWJz7 (ORCPT ); Fri, 23 Nov 2012 04:55:59 -0500 Received: from nat28.tlf.novell.com ([130.57.49.28]:45525 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964867Ab2KWJz6 convert rfc822-to-8bit (ORCPT ); Fri, 23 Nov 2012 04:55:58 -0500 Message-Id: <50AF567402000078000AABF6@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.1 Date: Fri, 23 Nov 2012 09:56:52 +0000 From: "Jan Beulich" To: "H. Peter Anvin" Cc: , , , , , , "Daniel Kiper" , , , , "Eric W. Biederman" Subject: Re: [PATCH v2 01/11] kexec: introduce kexec_ops struct References: <1353423893-23125-1-git-send-email-daniel.kiper@oracle.com> <1353423893-23125-2-git-send-email-daniel.kiper@oracle.com> <87lidwtego.fsf@xmission.com> <20121121105221.GA2925@host-192-168-1-59.local.net-space.pl> <87txshx28b.fsf@xmission.com> <50AE62E9.3000602@zytor.com> In-Reply-To: <50AE62E9.3000602@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1149 Lines: 24 >>> On 22.11.12 at 18:37, "H. Peter Anvin" wrote: > I actually talked to Ian Jackson at LCE, and mentioned among other > things the bogosity of requiring a PUD page for three-level paging in > Linux -- a bogosity which has spread from Xen into native. It's a page > wasted for no good reason, since it only contains 32 bytes worth of > data, *inherently*. Furthermore, contrary to popular belief, it is > *not* pa page table per se. > > Ian told me: "I didn't know we did that, and we shouldn't have to." > Here we have suffered this overhead for at least six years, ... Even the Xen kernel only needs the full page when running on a 64-bit hypervisor (now that we don't have a 32-bit hypervisor anymore, that of course basically means always). But yes, I too never liked this enforced over-allocation for native kernels (and was surprised that it was allowed in at all). Jan -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/