From: Nicolas Pitre <nicolas.pitre@linaro.org>
To: Stuart Longland <stuartl@longlandclan.id.au>
Cc: Andi Kleen <andi@firstfloor.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>,
linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 0/5] minitty: a minimal TTY layer alternative for embedded systems
Date: Sun, 2 Apr 2017 21:01:48 -0400 (EDT) [thread overview]
Message-ID: <alpine.LFD.2.20.1704022040380.1847@knanqh.ubzr> (raw)
In-Reply-To: <92fb1e4a-d6df-f55b-c0a1-9c1eb78e3943@longlandclan.id.au>
On Mon, 3 Apr 2017, Stuart Longland wrote:
> On 03/04/17 07:41, Nicolas Pitre wrote:
> >> No PTYs seems like a big limitation. This means no sshd?
> > Again, my ultimate system target is in the sub-megabyte of RAM. I
> > really doubt you'll be able to fit an SSH server in there even if PTYs
> > were supported, unless sshd (or dropbear) can be made really tiny.
> > Otherwise you most probably have sufficient resources to run the regular
> > TTY code.
>
> Are we talking small microcontrollers here? The smallest machine in
> terms of RAM I ever recall running Linux on was a 386SX/25 MHz with 4MB
> RAM, and that had a MMU.
Not to repeat what I've said already, I invite you to have a look at
https://lkml.org/lkml/2017/3/24/634
> I recall Slackware requiring that you booted with a mounted floppy (no
> ramdisk) and possibly even required that you had a second floppy drive
> formatted as swap so you'd be able to get through the install without
> oomkiller knocking on your door.
Did the oom killer even exist in those days? I don't remember.
All I remember is the stack of 73 flopies or so to install Slackware...
and of course floppy #68 would have developed a bad sector preventing
you from completing the installation.
> Sub-megabyte system support is a noble goal, but I'm wondering how
> practical such systems would be, and whether an embedded real-time
> kernel might be a better choice than Linux on such systems.
Obviously, you need to leave the idea of a _distribution_ behind. If you
think of a single user app, and a kernel that only provides those
syscalls used by that app, and the minimal subset of kernel services
that such an app require, then nothing prevents such and app/kernel from
using the actual Linux API. And that's where you get a big advantage
over other RTOSes. See the link above for the full rationale.
Nicolas
next prev parent reply other threads:[~2017-04-03 1:01 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-01 22:21 [PATCH v2 0/5] minitty: a minimal TTY layer alternative for embedded systems Nicolas Pitre
2017-04-01 22:21 ` [PATCH v2 1/5] console: move console_init() out of tty_io.c Nicolas Pitre
2017-04-01 22:21 ` [PATCH v2 2/5] tty: move baudrate handling code to a file of its own Nicolas Pitre
2017-04-01 22:21 ` [PATCH v2 3/5] serial: small Makefile reordering Nicolas Pitre
2017-04-02 12:55 ` Andy Shevchenko
2017-04-02 15:49 ` Nicolas Pitre
2017-04-01 22:21 ` [PATCH v2 4/5] serial: split generic UART driver helper functions into a separate file Nicolas Pitre
2017-04-02 13:16 ` Andy Shevchenko
2017-04-02 15:44 ` Nicolas Pitre
2017-04-03 7:35 ` kbuild test robot
2017-04-01 22:21 ` [PATCH v2 5/5] minitty: minimal TTY support alternative for serial ports Nicolas Pitre
2017-04-02 13:22 ` [PATCH v2 0/5] minitty: a minimal TTY layer alternative for embedded systems Andy Shevchenko
2017-04-02 15:55 ` Nicolas Pitre
2017-04-03 12:56 ` Alan Cox
2017-04-03 16:06 ` Nicolas Pitre
2017-04-03 18:05 ` Alan Cox
2017-04-03 19:50 ` Nicolas Pitre
2017-04-04 13:40 ` Alan Cox
2017-04-04 19:26 ` Nicolas Pitre
2017-04-02 20:47 ` Andi Kleen
2017-04-02 21:41 ` Nicolas Pitre
2017-04-02 22:44 ` Stuart Longland
2017-04-03 1:01 ` Nicolas Pitre [this message]
2017-04-04 0:39 ` Stuart Longland
2017-04-03 18:14 ` Geert Uytterhoeven
2017-04-03 18:57 ` Rob Herring
2017-04-03 19:46 ` Geert Uytterhoeven
2017-04-03 21:05 ` Andy Shevchenko
2017-04-04 16:59 ` Tom Zanussi
2017-04-04 17:08 ` Andy Shevchenko
2017-04-04 17:59 ` Tom Zanussi
2017-04-04 18:04 ` Andy Shevchenko
2017-04-04 18:31 ` Nicolas Pitre
2017-04-04 19:58 ` Tom Zanussi
2017-04-04 20:27 ` Nicolas Pitre
2017-04-04 18:53 ` Nicolas Pitre
2017-04-03 7:54 ` Andy Shevchenko
2017-04-03 15:31 ` Andi Kleen
2017-04-03 17:27 ` Nicolas Pitre
2017-04-03 19:57 ` Adam Borowski
2017-04-03 20:09 ` Nicolas Pitre
2017-04-03 20:32 ` Adam Borowski
2017-04-03 16:40 ` Nicolas Pitre
2017-04-03 7:44 ` Greg Kroah-Hartman
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