Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752188AbdDDAkl (ORCPT ); Mon, 3 Apr 2017 20:40:41 -0400 Received: from eth2015.qld.adsl.internode.on.net ([150.101.176.226]:34013 "EHLO atomos.longlandclan.id.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751734AbdDDAkj (ORCPT ); Mon, 3 Apr 2017 20:40:39 -0400 Subject: Re: [PATCH v2 0/5] minitty: a minimal TTY layer alternative for embedded systems To: Nicolas Pitre References: <20170401222119.25106-1-nicolas.pitre@linaro.org> <87pogur0y9.fsf@firstfloor.org> <92fb1e4a-d6df-f55b-c0a1-9c1eb78e3943@longlandclan.id.au> Cc: Andi Kleen , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org From: Stuart Longland Openpgp: id=BCA11879F4F93BE3DB0DEE72F954BBBB7948D546; url=https://stuartl.longlandclan.id.au/key.asc Message-ID: <821bef75-3c16-a7f2-ea15-de711d1d9eb8@longlandclan.id.au> Date: Tue, 4 Apr 2017 10:39:53 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="oWNojkaOe1c9c3pmGAB10GXQPJVqblwpX" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4877 Lines: 115 This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --oWNojkaOe1c9c3pmGAB10GXQPJVqblwpX Content-Type: multipart/mixed; boundary="QE0fHnkwqEFDcB2PqxKIt1p8Hn9nXhsd6" From: Stuart Longland To: Nicolas Pitre Cc: Andi Kleen , Greg Kroah-Hartman , Jiri Slaby , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Message-ID: <821bef75-3c16-a7f2-ea15-de711d1d9eb8@longlandclan.id.au> Subject: Re: [PATCH v2 0/5] minitty: a minimal TTY layer alternative for embedded systems References: <20170401222119.25106-1-nicolas.pitre@linaro.org> <87pogur0y9.fsf@firstfloor.org> <92fb1e4a-d6df-f55b-c0a1-9c1eb78e3943@longlandclan.id.au> In-Reply-To: --QE0fHnkwqEFDcB2PqxKIt1p8Hn9nXhsd6 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 03/04/17 11:01, Nicolas Pitre wrote: > 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=20 >>> really doubt you'll be able to fit an SSH server in there even if PTY= s=20 >>> were supported, unless sshd (or dropbear) can be made really tiny.=20 >>> Otherwise you most probably have sufficient resources to run the regu= lar=20 >>> 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 4M= B >> RAM, and that had a MMU. >=20 > Not to repeat what I've said already, I invite you to have a look at=20 > https://lkml.org/lkml/2017/3/24/634 >=20 >> 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. >=20 > 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...= =20 > and of course floppy #68 would have developed a bad sector preventing=20 > you from completing the installation. It probably didn't, my memory is a bit hazy, even though the machine in question was long obsolete by the time I did this experiment. The version of Slackware was pretty old by that time too. Luckily for me, I had a network, I could mount the CD disk sets over NFS that way, and so the only floppies I had to worry about were the boot and root floppies. But I digress=E2=80=A6 :-) >> 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. >=20 > Obviously, you need to leave the idea of a _distribution_ behind. If yo= u=20 > think of a single user app, and a kernel that only provides those=20 > syscalls used by that app, and the minimal subset of kernel services=20 > that such an app require, then nothing prevents such and app/kernel fro= m=20 > using the actual Linux API. And that's where you get a big advantage=20 > over other RTOSes. See the link above for the full rationale. Fair enough=E2=80=A6 so basically using the Linux kernel in place of an e= mbedded kernel like FreeRTOS or eCos. Still, as I say a noble goal, I wish the project well. I guess it can be our answer to RetroBSD. :-) --=20 Stuart Longland (aka Redhatter, VK4MSL) I haven't lost my mind... ...it's backed up on a tape somewhere. --QE0fHnkwqEFDcB2PqxKIt1p8Hn9nXhsd6-- --oWNojkaOe1c9c3pmGAB10GXQPJVqblwpX Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIcBAEBCAAGBQJY4utZAAoJEPlUu7t5SNVGuvwQAJ6EI+FFNCAn2dfscelm7h8T 2V7ikqMgVJyFqFvVvyFL8jkw8RyMg8+OlWb5h9MJfhs8Z2oWvjBBTmRIgq07r+FP jDqVpMQjP28pe+uXuL6uym6qAV8hfVjVje6oDaXhBhu8HPLD5usrtjfOnyDjo8xz Y5F5vpIA3NaGUbfWhLrr6w4HpLe9skyulUYTZkzUKO4SLSv/v3q+5kH5UZSZLn45 m6xygq6iqKEIfGs/p7D2DSVkjP+muwCk5i+i5iIZ6Vg53CZYXeGhIfXxn+ar9V0i NjPHjVEhu/PrTiz9U+G0wwqUtiSAdYCqK7QTpKYRJ33MJ0f2BLNQzwcZz8tAEob/ mHF/f0mU1zeQN09PfoYaKtsH+ns69bLwLwbx112N+A+P1n4MqPypcsnPaFe7wuWQ w/NdBLUvGsXYEQcFExUnhjBHDlZ4CNetpyEk3zLl6klDb8QmisW14WOtfZj9sCmq z8RSvzNNsWycWjTYjn0SWTeCdsqUz1FxxUqeMx15Lxfo0YiFQRAHzEdjapqE18lp FouOQFcOxL984/elRQwXiT7guhyS89od4jetzET8ScKhbtaisaRicQh617nTonI9 ogmJW8TsIhrIeL1aHheotVw+E8/LyCIuRHu5FLRKoul9zYht6gMIlKJKMy+LMpz3 WH7gWV5+oZyvMSh+YuZp =8q1C -----END PGP SIGNATURE----- --oWNojkaOe1c9c3pmGAB10GXQPJVqblwpX--