From mboxrd@z Thu Jan 1 00:00:00 1970 From: Konrad Rzeszutek Wilk Subject: [PATCH] Two patches fixing regression introduced by 'x86-64, mm: Put early page table high' Date: Mon, 2 May 2011 13:22:20 -0400 Message-ID: <1304356942-17656-1-git-send-email-konrad.wilk@oracle.com> Return-path: Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, stefano.stabellini@eu.citrix.com, yinghai@kernel.org, hpa@zytor.com Cc: xen-devel@lists.xensource.com List-Id: xen-devel@lists.xenproject.org In a couple of days I thinking to ask Linus to pull this branch: git://git.kernel.org/pub/scm/linux/kernel/git/konrad/xen.git stable/bug-fixes-for-rc5 Which as two fixes that fix a bootup (Linux can't boot under Xen at all) regression introduced by "x86-64, mm: Put early page table high" (git commit 4b239f458c229de044d6905c2b0f9fe16ed9e01e). Stefano and Yinghai have been working on patches fixing this regression when the patch was still in x86/mm-core before the 2.6.39 merge window openned. But we haven't come up with an acceptable general solution yet, so this patchset provides a workaround for the problem. Peter, Yinghai - what would be the best forum/email/conference to hammer out a general solution for this? Currently, there are couple of ways of fixing this: - use pvops hooks: http://marc.info/?i=1302607192-21355-2-git-send-email-stefano.stabellini@eu.citrix.com - have a workaround in Xen MMU's early bootup code (which is what these two patches to this email have). - or remove the patch introducing the regression altogether. Foremost important is to fix the regression, and attached patches achieve that. I want to remove this workaround patch when we hammer out more appropriate semantics for the page table creation - but that will take some time and the runway to do that in 2.6.39 is gone. Konrad Rzeszutek Wilk (1): xen/mmu: Add workaround "x86-64, mm: Put early page table high" Stefano Stabellini (1): xen: mask_rw_pte mark RO all pagetable pages up to pgt_buf_top arch/x86/xen/mmu.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++++++- 1 files changed, 124 insertions(+), 1 deletions(-)