From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1WT7bj-00018G-LL for kexec@lists.infradead.org; Thu, 27 Mar 2014 10:32:25 +0000 Date: Thu, 27 Mar 2014 18:31:54 +0800 From: WANG Chao Subject: Re: [PATCH v4 0/4] kexec-tools, x86: E820 memmap pass for kdump Message-ID: <20140327103154.GA2944@dhcp-17-89.nay.redhat.com> References: <1395216241-13983-1-git-send-email-chaowang@redhat.com> <20140320154228.GB29549@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20140320154228.GB29549@redhat.com> 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" Errors-To: kexec-bounces+dwmw2=twosheds.infradead.org@lists.infradead.org To: Vivek Goyal Cc: kexec@lists.infradead.org, horms@verge.net.au, linn@hp.com, hpa@zytor.com, dyoung@redhat.com, trenn@suse.de, ebiederm@xmission.com Hi, Vivek Sorry for my late response. On 03/20/14 at 11:42am, Vivek Goyal wrote: > On Wed, Mar 19, 2014 at 04:03:57PM +0800, WANG Chao wrote: > > Hi, All > > > > When kaslr comes in and kdump is broken, it seems about the right time to use > > E820 instead of memmap=exactmap to pass memmap for kdump for the default memmap > > passing mechanism: > > http://lists.infradead.org/pipermail/kexec/2014-February/011048.html > > What's the connection between kaslr and passing memory mappings in > bootparams? kaslr doesn't work with memmap=exactmap. kaslr happens before parsing user defined memmap and it walks through E820 in boot_params to determine 2nd kernel text area. And it would override the 1st kernel's ram. > > To me this is completely independent of kaslr. This is moving towards > a better design to pass memory map to second kernel which in turn will > also solve the issue of too many memory ranges on large machines. Yes. You're right. That's what this patchset is mostly for. kASLR is just one of the reasons. > > Also, could you get hold of a machine with calgary IOMMU and test that > --pass-memmap option makes those calgary machines work? I couldn't find any calgary box. I tried to force calgary iommu on some IBM-X series, but didn't work out. Those old hardwares are really hard to find these days. I think given the fact that the calgary code chage is simple enough and hpa has committed to tip tree, this patchset won't risk much. Thanks WANG Chao _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec