From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from cantor2.suse.de ([195.135.220.15] helo=mx2.suse.de) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1Tzzf0-0005sW-DF for kexec@lists.infradead.org; Tue, 29 Jan 2013 01:06:51 +0000 From: Thomas Renninger Subject: Re: [PATCH 2/2] x86 e820: Introduce memmap=resetusablemap for kdump usage Date: Tue, 29 Jan 2013 02:05:53 +0100 Message-ID: <6950516.1uefDuthAH@hammer82.arch.suse.de> In-Reply-To: References: <1358868049-19884-1-git-send-email-trenn@suse.de> MIME-Version: 1.0 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: Yinghai Lu Cc: x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, horms@verge.net.au, "H. Peter Anvin" , vgoyal@redhat.com On Wednesday, January 23, 2013 08:07:19 PM Yinghai Lu wrote: > On Tue, Jan 22, 2013 at 12:06 PM, Yinghai Lu wrote: > > On Tue, Jan 22, 2013 at 8:32 AM, H. Peter Anvin wrote: > >>> Again: Please explain what is bad with this solution. > >>> I cannot see a better and more robust way for kdump other than > >>> reserving the original reserved memory areas as declared by the BIOS. > >> > >> It is bad because it creates more complexity than is needed. > >> > >> The whole point is that what we want is simply to switch type 1 to type > >> X, with the sole exceptions being the areas explicitly reserved for the > >> kdump kernel. > > > > Do you prefer to "reserveram" way in attached patch? > > Hi, Thomas, > > Can you please check attached reserveram version on your setup? > > If it is ok, i will put it in for-x86-boot patchset and send it to > Peter for v3.9. But this (converting usable memory to reserved one before usable kdump memory is added) will let machines run into problems again for which the check: "mmconf area must be in reserved memory" got added? If, then memory which was usable before has to be converted to a special E820_KUMP (or whatever type) to make sure existing checks which look for "is reserved memory" still work the same way as in a productive kernel. Advantage of this would be that the info what originally was usable memory is preserved and can be used in future kdump related patches. So I guess the final patch should be: - Add a new e820 type: E820_KDUMP_RESERVED /* Originally usable memory where the crashed kernel kernel resided in */ - Use Yinghai's last posted patch, but instead of: + e820_update_range(0, ULLONG_MAX, E820_RAM, + E820_RESERVED); ... + e820_remove_range(start_at, mem_size, E820_RESERVED, 0); do: + e820_update_range(0, ULLONG_MAX, E820_RAM, + E820_KDUMP_RESERVED); ... + e820_remove_range(start_at, mem_size, E820_KDUMP_RESERVED, 0); - Come up with another memmap=kdump_reserve_ram memmap option name or however it should get named... If this proposal gets accepted, I can send a tested patch... Thomas _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec