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From: Josh Triplett <josh@joshtriplett.org>
To: Menglong Dong <menglong8.dong@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
	Luis Chamberlain <mcgrof@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Kees Cook <keescook@chromium.org>,
	Sami Tolvanen <samitolvanen@google.com>,
	ojeda@kernel.org, johan@kernel.org,
	Bjorn Helgaas <bhelgaas@google.com>,
	masahiroy@kernel.org, Menglong Dong <dong.menglong@zte.com.cn>,
	joe@perches.com, Jens Axboe <axboe@kernel.dk>,
	hare@suse.de, Jan Kara <jack@suse.cz>,
	tj@kernel.org, gregkh@linuxfoundation.org, song@kernel.org,
	NeilBrown <neilb@suse.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	f.fainelli@gmail.com, arnd@arndb.de,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	wangkefeng.wang@huawei.com, Barret Rhoden <brho@google.com>,
	mhiramat@kernel.org, Steven Rostedt <rostedt@goodmis.org>,
	vbabka@suse.cz, Alexander Potapenko <glider@google.com>,
	pmladek@suse.com, Chris Down <chris@chrisdown.name>,
	jojing64@gmail.com, terrelln@fb.com, geert@linux-m68k.org,
	mingo@kernel.org, linux-fsdevel@vger.kernel.org,
	LKML <linux-kernel@vger.kernel.org>,
	jeyu@kernel.org
Subject: Re: [PATCH v2 2/3] init/do_cmounts.c: introduce 'user_root' for initramfs
Date: Wed, 26 May 2021 15:33:25 -0700	[thread overview]
Message-ID: <YK7MtZz8sklOMPKo@localhost> (raw)
In-Reply-To: <CADxym3bznknEWLaa-SgYZAsTGucP_9m+9=JW7oc6=ggrUaBk7A@mail.gmail.com>

On Wed, May 26, 2021 at 04:33:00PM +0800, Menglong Dong wrote:
> On Wed, May 26, 2021 at 12:33 PM Josh Triplett <josh@joshtriplett.org> wrote:
> >
> > On Tue, May 25, 2021 at 10:23:09PM -0500, Eric W. Biederman wrote:
> > > If we are going to do this something that is so small and clean it can
> > > be done unconditionally always.
> > [...]
> > > The net request as I understand it: Make the filesystem the initramfs
> > > lives in be an ordinary filesystem so it can just be used as the systems
> > > primary filesystem.
> >
> > Including the ability to pivot_root it away, which seems like the main
> > sticking point.
> >
> > If this can be done without any overhead, that seems fine, but if this
> > involves mounting an extra filesystem, that may add an appreciable
> > amount of boot time for systems trying to boot in milliseconds. (Such
> > systems would not use an initramfs if they're going to go on and boot a
> > separate root filesystem, but they can use an initramfs as their *only*
> > filesystem.)
> 
> Compared to the time the unpacking spent, a mounting seems nothing. In the
> scene above, this change can be disabled by kconfig, if pivot_root
> is not needed in initramfs.

The initramfs could be as small as one file.

  parent reply	other threads:[~2021-05-26 22:33 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-25 14:15 [PATCH v2 0/3] init/initramfs.c: make initramfs support pivot_root menglong8.dong
2021-05-25 14:15 ` [PATCH v2 1/3] init/main.c: introduce function ramdisk_exec_exist() menglong8.dong
2021-05-25 14:15 ` [PATCH v2 2/3] init/do_cmounts.c: introduce 'user_root' for initramfs menglong8.dong
2021-05-25 18:49   ` Eric W. Biederman
2021-05-26  1:51     ` Menglong Dong
2021-05-26  3:23       ` Eric W. Biederman
2021-05-26  4:32         ` Josh Triplett
2021-05-26  8:33           ` Menglong Dong
2021-05-26  9:03             ` Luis Chamberlain
2021-05-27  7:29               ` Menglong Dong
2021-05-26 22:33             ` Josh Triplett [this message]
2021-05-26  8:23         ` Menglong Dong
2021-05-25 14:15 ` [PATCH v2 3/3] init/do_mounts.c: fix rootfs_fs_type with ramfs menglong8.dong
2021-05-25 17:43 ` [PATCH v2 0/3] init/initramfs.c: make initramfs support pivot_root Josh Triplett
2021-05-28  7:10 ` Masami Hiramatsu
2021-05-28  7:37   ` Menglong Dong

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