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From: Peter Korsgaard <peter@korsgaard.com>
To: buildroot@busybox.net
Subject: [Buildroot] [RFC 3/6] system: add mdev-only /dev management (without devtmpfs)
Date: Tue, 15 Sep 2015 14:32:37 +0200	[thread overview]
Message-ID: <87fv2fvp5m.fsf@dell.be.48ers.dk> (raw)
In-Reply-To: <55F80E9C.7070208@mind.be> (Arnout Vandecappelle's message of "Tue, 15 Sep 2015 14:27:08 +0200")

>>>>> "Arnout" == Arnout Vandecappelle <arnout@mind.be> writes:

Hi,

 > On 15-09-15 14:01, Peter Korsgaard wrote:
 >> Or alternatively, extend the S10mdev logic to detect that it need to
 >> create a tmpfs on /dev (by looking for devtmpfs in /proc/filesystems or
 >> detecting that /dev is RO) and have all the fixup there. That way it
 >> atleast doesn't add any more complications to the rest of Buildroot /
 >> users.

 >  That's a great idea, because it actually simplifies the buildroot code (no
 > longer needed to force devtmpfs in the kernel when mdev is selected).

 >  To detect, it's as simple as:

 > if [ "$(cut -d ' ' -f 2,3 /proc/mounts | sed -n '/^\/dev /s///p')" != devtmpfs ]

Or simply 'grep -q devtmpfs /proc/filesystems'. It doesn't check if /dev
is really a devtmpfs, but as we force DEVTMPFS_MOUNT=y (and the cpio
init wrapper) that is probably good enough.

For mdev, I think it makes more sense to check if /dev is writable, as
that is the really what mdev requires (E.G. we could be in an initramfs
on a <2.6.32 kernel or similar.

-- 
Venlig hilsen,
Peter Korsgaard 

  reply	other threads:[~2015-09-15 12:32 UTC|newest]

Thread overview: 49+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-08 21:28 [Buildroot] [RFC 0/6] mdev-only /dev management (without devtmpfs) Luca Ceresoli
2015-09-08 21:28 ` [Buildroot] [RFC 1/6] Move mounting /sys from fstab to inittab Luca Ceresoli
2015-09-09  9:12   ` Arnout Vandecappelle
2015-09-08 21:28 ` [Buildroot] [RFC 2/6] system: clarify /dev management using devtmpfs + {mdev, eudev} Luca Ceresoli
2015-09-09  9:40   ` Arnout Vandecappelle
2015-09-09 10:53     ` Luca Ceresoli
2015-09-09 10:54       ` Arnout Vandecappelle
2015-09-08 21:28 ` [Buildroot] [RFC 3/6] system: add mdev-only /dev management (without devtmpfs) Luca Ceresoli
2015-09-09  9:21   ` Arnout Vandecappelle
2015-09-09 12:29     ` Luca Ceresoli
2015-09-09 12:32       ` Arnout Vandecappelle
2015-09-09 13:54       ` Thomas Petazzoni
2015-09-14 13:47         ` Luca Ceresoli
2015-09-14 22:23           ` Arnout Vandecappelle
2015-09-15 22:35             ` Luca Ceresoli
2015-09-14 20:53         ` Peter Korsgaard
2015-09-14 21:34           ` Thomas Petazzoni
2015-09-14 21:38             ` Peter Korsgaard
2015-09-15  7:30               ` Thomas Petazzoni
2015-09-15  8:09                 ` Peter Korsgaard
2015-09-15  9:41                   ` Thomas Petazzoni
2015-09-15 12:01                     ` Peter Korsgaard
2015-09-15 12:27                       ` Arnout Vandecappelle
2015-09-15 12:32                         ` Peter Korsgaard [this message]
2015-09-18 16:37                           ` Luca Ceresoli
2015-09-15 13:03                         ` Thomas Petazzoni
2015-09-15 13:14                           ` Peter Korsgaard
2015-09-15 22:34                       ` Luca Ceresoli
2015-10-01  9:36                       ` Luca Ceresoli
2015-10-01 10:03                         ` Peter Korsgaard
2015-09-15 22:31                   ` Luca Ceresoli
2015-09-16  7:32                     ` Peter Korsgaard
2015-09-18 15:47                       ` Luca Ceresoli
2015-09-09  9:34   ` Arnout Vandecappelle
2015-09-09 11:23     ` Thomas Petazzoni
2015-09-09 11:29   ` Thomas Petazzoni
2015-09-09 20:33     ` Arnout Vandecappelle
2015-09-14 16:07       ` Luca Ceresoli
2015-09-14 16:05     ` Luca Ceresoli
2015-09-14 19:34       ` Thomas Petazzoni
2015-09-14 20:19         ` Arnout Vandecappelle
2015-09-15 22:07           ` Luca Ceresoli
2015-09-08 21:28 ` [Buildroot] [RFC 4/6] system: strip the initial /dev for mdev-only /dev management Luca Ceresoli
2015-09-08 21:28 ` [Buildroot] [RFC 5/6] docs/manual: document "Dynamic using mdev only" " Luca Ceresoli
2015-09-09 10:39   ` Arnout Vandecappelle
2015-09-08 21:28 ` [Buildroot] [RFC 6/6] **** DO NOT COMMIT THIS **** ugly stuff to test mdev-only " Luca Ceresoli
2015-09-09  9:26 ` [Buildroot] [RFC 0/6] mdev-only /dev management (without devtmpfs) Arnout Vandecappelle
2015-09-09 11:30   ` Thomas Petazzoni
2015-09-14 21:03 ` Peter Korsgaard

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