archive mirror
 help / color / mirror / Atom feed
From: Kees Cook <>
To: Mike Snitzer <>
Cc: Will Drewry <>,
	"open list:DOCUMENTATION" <>,
	Richard Weinberger <>,
	device-mapper development <>,
	LKML <>,,,
	Enric Balletbo i Serra <>,, Alasdair G Kergon <>
Subject: Re: [linux-lvm] [PATCH 0/2] boot to a mapped device
Date: Thu, 27 Sep 2018 09:36:23 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On Thu, Sep 27, 2018 at 7:23 AM, Mike Snitzer <> wrote:
> On Wed, Sep 26 2018 at  3:16am -0400,
> Richard Weinberger <> wrote:
>> Helen,
>> On Wed, Sep 26, 2018 at 7:01 AM Helen Koike <> wrote:
>> >
>> > This series is reviving an old patchwork.
>> > Booting from a mapped device requires an initramfs. This series is
>> > allows for device-mapper targets to be configured at boot time for
>> > use early in the boot process (as the root device or otherwise).
>> What is the reason for this patch series?
>> Setting up non-trivial root filesystems/storage always requires an
>> initramfs, there is nothing
>> wrong about this.
> Exactly.  If phones or whatever would benefit from this patchset then
> say as much.

I think some of the context for the series was lost in commit logs,
but yes, both Android and Chrome OS do not use initramfs. The only
thing that was needed to do this was being able to configure dm
devices on the kernel command line, so the overhead of a full
initramfs was seen as a boot time liability, a boot image size
liability (e.g. Chrome OS has a limited amount of storage available
for the boot image that is covered by the static root of trust
signature), and a complexity risk: everything that is needed for boot
could be specified on the kernel command line, so better to avoid the
whole initramfs dance.

So, instead, this plumbs the dm commands directly instead of bringing
up a full userspace and performing ioctls.

> I will not accept this patchset at this time.
>> > Example, the following could be added in the boot parameters.
>> > dm="lroot,,,rw, 0 4096 linear 98:16 0, 4096 4096 linear 98:32 0" root=/dev/dm-0
>> Hmmm, the new dm= parameter is anything but easy to get right.
> No, it isn't.. exposes way too much potential for users hanging
> themselves.

IIRC, the changes in syntax were suggested back when I was trying to
drive this series:

And it matches the "concise" format in dmsetup:;a=commit;h=827be01758ec5adb7b9d5ea75b658092adc65534

What do you feel are next steps?



Kees Cook
Pixel Security

  reply	other threads:[~2018-09-27 16:36 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-26  5:00 [linux-lvm] [PATCH 0/2] boot to a mapped device Helen Koike
2018-09-26  5:00 ` [linux-lvm] [PATCH 1/2] dm ioctl: add a device mapper ioctl function Helen Koike
2018-09-26  5:00 ` [linux-lvm] [PATCH 2/2] init: add support to directly boot to a mapped device Helen Koike
2018-09-26 16:09   ` Randy Dunlap
2018-09-26  5:02 ` [linux-lvm] [PATCH 0/2] " Helen Koike
2018-09-26  7:16 ` Richard Weinberger
2018-09-27 14:23   ` Mike Snitzer
2018-09-27 16:36     ` Kees Cook [this message]
2018-09-27 18:31       ` Mike Snitzer
2018-10-19 16:27         ` Helen Koike

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).