From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from out01.mta.xmission.com ([166.70.13.231]) by merlin.infradead.org with esmtp (Exim 4.76 #1 (Red Hat Linux)) id 1TZx0B-0000AQ-Bi for kexec@lists.infradead.org; Sun, 18 Nov 2012 05:01:03 +0000 From: ebiederm@xmission.com (Eric W. Biederman) 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> <50A86A4D.8090503@zytor.com> Date: Sat, 17 Nov 2012 21:00:08 -0800 In-Reply-To: <50A86A4D.8090503@zytor.com> (H. Peter Anvin's message of "Sat, 17 Nov 2012 20:55:41 -0800") Message-ID: <87haonqzdz.fsf@xmission.com> MIME-Version: 1.0 Subject: Re: [PATCH 3/8] add mem64_min/max control List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: kexec-bounces@lists.infradead.org Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: "H. Peter Anvin" Cc: Haren Myneni , Simon Horman , Yinghai Lu , kexec@lists.infradead.org, Vivek Goyal "H. Peter Anvin" writes: > 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. Whatever works. It sounds like six of one half a dozen of the other to me. Last I looked early_ioremap works as soon as paging is enabled on x86_64. Eric _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec