From owner-freebsd-xen@freebsd.org Wed Apr 12 05:30:02 2017 Return-Path: Delivered-To: freebsd-xen@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id E5F27D3A204 for ; Wed, 12 Apr 2017 05:30:02 +0000 (UTC) (envelope-from bilbo@hobbiton.org) Received: from mail-qk0-x244.google.com (mail-qk0-x244.google.com [IPv6:2607:f8b0:400d:c09::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id A7F20C3 for ; Wed, 12 Apr 2017 05:30:02 +0000 (UTC) (envelope-from bilbo@hobbiton.org) Received: by mail-qk0-x244.google.com with SMTP id d131so2622472qkc.0 for ; Tue, 11 Apr 2017 22:30:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=hobbiton-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=5pvMK+qfhOzxxmmQPnHuAbWBL4BOFhXnZC0GAPB7njU=; b=xN0UYjeZUI7AyJWxjFZL0R7i7Z/ZxqMYAEOpq7c6kIkXrgNpTZpUxDxp+vte3AGuGr iGtTz0+IH2QBTau8RJrynWPdKcW/BjOBwhC6WNzsdpN5Zd9RAJ7DTEQB/zY88QLP5Hji 7n/XluPCQ5eHNqOUVc2gb5uEO7x9HkgrTobB07tTPl7W3jGYKRZk4uf4g2nIU+bukUbH Oa5zPBBbghg2gnHsfWaLjZdrJMs7QQVHD+rbbMRZs6KFQTennVnf2tUcPZsubMXdCXR1 GRGQvu064COXOGAart1STPZxDJiMss/qII2EteSvI4ySPMGdl2D948sMIx/BFgCJkEOs SV/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=5pvMK+qfhOzxxmmQPnHuAbWBL4BOFhXnZC0GAPB7njU=; b=UHCzUXF5c4AwoDfVTpisiMkxnXNiEBowBIgoQB1o6I88edgH/OIpqRbT/A6lrHLZsi YKHvDMl7NcwoKvx54F4h6ygBz4VQbV/tWcsFpQn7aJzqJoA2IbMDVucjWg7ncmx7dEiH HPx2CigH71d5I1i6xSxYScGZUOOYN0FoB30k89g6hruUZOYFNWn8v7qBgEo+zLtHRbpN O72pgTYPTGkFPQnXGhifslvOPiBTpEmoZtNGf51IQhzxVU7+C4AYoEeBjotZXboHd24/ xaosh5e1n0Y8UegEBPfZCobz5dEIcyt2LadZ0PjG5CGHkpARsFekCwAHppqOIALlhYlD cQHQ== X-Gm-Message-State: AFeK/H2f9Q4Id9PxzCKmRHgFmucHF+o5lPYnPWE/7MCDCwZJK9W4WP2uqmpPOL7nD+aBgUiNdBsNFa58QhVIIQ== X-Received: by 10.55.189.130 with SMTP id n124mr61993992qkf.235.1491975001677; Tue, 11 Apr 2017 22:30:01 -0700 (PDT) MIME-Version: 1.0 Received: by 10.12.135.246 with HTTP; Tue, 11 Apr 2017 22:30:00 -0700 (PDT) X-Originating-IP: [208.72.151.19] Received: by 10.12.135.246 with HTTP; Tue, 11 Apr 2017 22:30:00 -0700 (PDT) In-Reply-To: <0100015b6070c546-05c6cf24-36e1-487f-be5e-b2bb6efd4472-000000@email.amazonses.com> References: <0100015b6070c546-05c6cf24-36e1-487f-be5e-b2bb6efd4472-000000@email.amazonses.com> From: Leif Pedersen Date: Wed, 12 Apr 2017 00:30:00 -0500 Message-ID: Subject: Re: amazon/xen... any way at all to pass a message/signal/semaphoere/morse-code to the boot loader? To: freebsd-cloud@freebsd.org Cc: Toomas Soome , Julian Elischer , freebsd-xen@freebsd.org Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: freebsd-xen@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Discussion of the freebsd port to xen - implementation and usage List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 12 Apr 2017 05:30:03 -0000 I keep an extra EBS volume handy that has a simple recovery image. If I get stuck into a trouble, I change the normal boot disk to sdb, and attach my recovery volume as sda1. Essentially, the extra volume is my "recovery partition". To make it cheaper, keep only a snapshot of it. Same idea on Google Compute Engine. On Apr 11, 2017 11:34 PM, "Colin Percival" wrote: > [CCing freebsd-cloud, which is the right place for discussions of > FreeBSD/EC2] > > On 04/11/17 21:03, Julian Elischer wrote: > > In Amazon ec2 they have no console access (though I heard rumors that it > was > > available I have not seen any sign of it) so I'd like to put a "recovery > > partition" into an AMI. > > The trick is how to convince it to boot to that instead of the regular > action. > > Can you get what you want via gptboot's support for selecting the partition > to boot via "bootonce" and "bootme" flags? > > > The ideal thing would be if there was way to 'influence' one of the > smbios > > values in some way, and have the boot code see it, but I'm open to any > > suggestions. > > I really need only 1 bit of information to get through. > > > > Possibilties include "changing the VM to have only 2G of ram" (we'd > never do > > that in a real machine). > > or maybe temporarily removing all the disks other than the root drive? > Almost > > anything I could do to signal the boot code to behave differently. > > I don't think adding/removing disks will be useful, since the extra disks > will > be Xen blkfront devices; AFAIK the boot loader doesn't know anything about > these. (The boot device is also a blkfront device but gets ATA emulation > for > the benefit of boot loaders.) > > Maybe you can repurpose some of the logic used for booting over NFS? I've > never heard of people booting over NFS when the initial bootstrap comes > from > disk rather than PXE, but I assume it's possible...? > > -- > Colin Percival > Security Officer Emeritus, FreeBSD | The power to serve > Founder, Tarsnap | www.tarsnap.com | Online backups for the truly paranoid > _______________________________________________ > freebsd-cloud@freebsd.org mailing list > https://lists.freebsd.org/mailman/listinfo/freebsd-cloud > To unsubscribe, send any mail to "freebsd-cloud-unsubscribe@freebsd.org" >