Date: Mon, 27 Feb 2017 11:01:24 -0700 From: Warner Losh <imp@bsdimp.com> To: Allan Jude <allanjude@freebsd.org> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Saurav Sachidanand <sauravsachidanand@gmail.com>, soc-admins@freebsd.org Subject: Re: [GSoC 2017] Original proposal: Port kernel Lua to FreeBSD Message-ID: <CANCZdfpiiJLyLbEQnk86mfwf07JGByq5oT_1-T43iEhscEEgMg@mail.gmail.com> In-Reply-To: <244231A2-EB18-4E58-A2B2-927F55D54950@FreeBSD.org> References: <CACKq%2BiX_V2MY9sNf-buEOO1S87dbhDv%2BPGbUEqRUVkvzz3pdvw@mail.gmail.com> <244231A2-EB18-4E58-A2B2-927F55D54950@FreeBSD.org>
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On Mon, Feb 27, 2017 at 8:26 AM, Allan Jude <allanjude@freebsd.org> wrote: > On February 27, 2017 5:28:41 AM PST, Saurav Sachidanand <sauravsachidanand@gmail.com> wrote: >>Hello FreeBSD community, >> >>I'm >> Saurav Sachidanand, and I'm >> a CS sophomore studying in India >>. >>I have an interest in operating systems development and wish to >>contribute >>to the FreeBSD community. I'm proficient with C and have some >>experience in >>kernel programming. Hence, I'd like to propose an original project for >>GSoC >>2017 that I feel would benefit this community. >> >>In past years, the Lua interpreter was ported to run inside the Linux >>and >>NetBSD kernel [1]. Lua was chosen because it's interpreter is very >>small (~240 >>KB) compared to that of Python or Ruby, it's MIT licensed, and is >>almost >>freestanding. A working demonstration of it is a packet filtering >>algorithm >>written entirely in kernel Lua [2]. >> >>Specifically, my proposal would be to port the following that are >>currently >>written for NetBSD: >>- the modified Lua VM source code with _KERNEL preprocessor directives >>to >>exclude user-space functionality like floating point, the io and os >>module >>in the standard library, etc. [3] >>- the kernel module device driver for /dev/lua, to which Lua scripts >>are >>fed to be executed [4], [5] >>- the luactl user-space program to control the Lua device and a couple >>of >>sysctl variables which serve similar purpose [6], [7] >> >>And then: >>- run the Lua test suite targeting whatever we support in the kernel to >>make sure it works [8] >>- and write Lua bindings to the kernel interfaces that would interest >>the >>FreeBSD community >> >>Since NetBSD and FreeBSD have similar kernel interfaces (mutexes, >>linked >>lists, device switch interface), the porting shouldn't involve too much >>code refactoring. Also, this would all be an experiment in that we >>don't >>fully know what the real world use cases might be, but it would attract >>more people to writing kernel code who otherwise wouldn't because of >>having >>to do everything in C. And it would be interesting to carry out it out >>in >>FreeBSD as well since it has a larger community than NetBSD. >> >>I humbly request anyone who is interested in this project to be my >>potential mentor(s) for GSoC. >> >>More slides on kernel Lua in NetBSD - [9], [10]. >> >>Thanks, >>Saurav >> >>[1] - http://www.netbsd.org/~lneto/dls14.pdf >>[2] - https://www.netbsd.org/~lneto/eurobsdcon14.pdf >>[3] - https://github.com/jsonn/src/tree/trunk/external/mit/lua/dist/src >>[4] - >>https://github.com/IIJ-NetBSD/netbsd-src/tree/master/sys/modules/lua >>[5] - >>https://github.com/IIJ-NetBSD/netbsd-src/tree/master/sys/modules/luasystm >>[6] - https://github.com/IIJ-NetBSD/netbsd-src/tree/master/sbin/luactl >>[7] - http://netbsd.gw.com/cgi-bin/man-cgi?lua+4+NetBSD-current >>[8] - http://www.lua.org/tests/ >>[9] - >>https://www.netbsd.org/gallery/presentations/mbalmer/fosdem2012/kernel_mode_lua.pdf >>[10] - https://www.lua.org/wshop13/Cormack.pdf >>_______________________________________________ >>freebsd-hackers@freebsd.org mailing list >>https://lists.freebsd.org/mailman/listinfo/freebsd-hackers >>To unsubscribe, send any mail to >>"freebsd-hackers-unsubscribe@freebsd.org" > > This may be quite a nice thing to have. Another upcoming use for LUA in the kernel is ZFS Channel Programs. These allow a number of ZFS operations to be completed as a single atomic transaction. > > I would hope we could structure this in such a way as to not end up with two copies of Lua in the kernel. There's also a 3/4 finished lua in the boot loader that you might be able to leverage as well.... Warner
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