From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from terminus.zytor.com ([2001:1868:205::10] helo=mail.zytor.com) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1TZwv4-0008Oa-14 for kexec@lists.infradead.org; Sun, 18 Nov 2012 04:55:46 +0000 Message-ID: <50A86A4D.8090503@zytor.com> Date: Sat, 17 Nov 2012 20:55:41 -0800 From: "H. Peter Anvin" MIME-Version: 1.0 Subject: Re: [PATCH 3/8] add mem64_min/max control References: <1353107067-14564-1-git-send-email-yinghai@kernel.org> <1353107067-14564-4-git-send-email-yinghai@kernel.org> <87haoo21mw.fsf@xmission.com> <87fw48zldz.fsf@xmission.com> <50A86563.30303@zytor.com> <876253sej9.fsf@xmission.com> In-Reply-To: <876253sej9.fsf@xmission.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: "Eric W. Biederman" Cc: Haren Myneni , Simon Horman , Yinghai Lu , kexec@lists.infradead.org, Vivek Goyal On 11/17/2012 08:47 PM, Eric W. Biederman wrote: >> >> I don't think that is feasible; we need access to this structure >> extremely early. I think if you're using the 64-bit entry point it >> has to be an entry condition that those structures are mapped. It >> simply becomes a precondition for using the 64-bit entry point. > > 64bit purgatory coming from kexec should be running with a page table > that identity maps everything loaded by kexec and in practice all of > memory. > > We should still be using that page table when we enter the new kernel. > > However then the 64bit kernel switches to it's own page tables. > > So after that point we potentially need early_ioremap, because the > kernel's page tables may not have covered the boot_params. Certainly we > need to do something to ensure the kernels page table covers boot_params. > The easy way to fix that is to do what we do on 32 bits: we copy it into the bss before we turn paging on (the 64-bit equivalent is before we switch to the new page tables.) That way we know where it is, at least for the bounded-size data items. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec