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Date:      Wed, 1 Mar 2017 16:08:23 +0000
From:      Saurav Sachidanand <sauravsachidanand@gmail.com>
To:        Warner Losh <imp@bsdimp.com>
Cc:        Ian Lepore <ian@freebsd.org>, Julian Elischer <julian@freebsd.org>,  Allan Jude <allanjude@freebsd.org>,  "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>
Subject:   Re: [GSoC 2017] Original proposal: Port kernel Lua to FreeBSD
Message-ID:  <CACKq%2BiVMd0edbOpg2Hr1bDdFmwekqt78YiCWbaY-iC16gqOW5g@mail.gmail.com>
In-Reply-To: <CANCZdfoYk1v9axkT0CqUbCWOaoPrEDoJRPpPk0kk5GDjDE=-fw@mail.gmail.com>
References:  <CACKq%2BiX_V2MY9sNf-buEOO1S87dbhDv%2BPGbUEqRUVkvzz3pdvw@mail.gmail.com> <244231A2-EB18-4E58-A2B2-927F55D54950@FreeBSD.org> <CANCZdfpiiJLyLbEQnk86mfwf07JGByq5oT_1-T43iEhscEEgMg@mail.gmail.com> <f221e624-1342-7548-a3f9-806a1d25b90d@freebsd.org> <1488383213.60166.10.camel@freebsd.org> <CANCZdfoYk1v9axkT0CqUbCWOaoPrEDoJRPpPk0kk5GDjDE=-fw@mail.gmail.com>

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Is it related to this project
https://wiki.freebsd.org/SummerOfCode2014/LuaLoader ?
Apparently, that project created a generic interface in the bootloader
to plug in any
interpreter, and then added Lua.

How about adding Python as well, as a GSoC project? A team from Intel managed to
get Python to run inside GRUB [1] [2]. I can use their work as a
reference for modifying
the Python interpreter.

[1] - https://lwn.net/Articles/641244/
[2] - https://github.com/biosbits/bits

On Wed, Mar 1, 2017 at 3:51 PM, Warner Losh <imp@bsdimp.com> wrote:
> On Wed, Mar 1, 2017 at 8:46 AM, Ian Lepore <ian@freebsd.org> wrote:
>> On Wed, 2017-03-01 at 16:14 +0800, Julian Elischer wrote:
>>> On 28/2/17 2:01 am, Warner Losh wrote:
>>> >
>>> > 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 <sauravsa
>>> > > chidanand@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/module
>>> > > > s/lua
>>> > > > [5] -
>>> > > > https://github.com/IIJ-NetBSD/netbsd-src/tree/master/sys/module
>>> > > > s/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....
>>> I'd like to see that finished. While Devin has done Heroic work with
>>> the forth in the loader, I think it's time has come.
>>> It' be nice to have something a little less '60s.
>>>
>>> >
>>> >
>>> > Warner
>>
>> I was under the impression that the "lua in bootloader" work was
>> basically done and just needed testing, which nobody has done.  I think
>> it's all sitting in the projects/lua-bootloader branch in svn.
>
> The branch compiles. Testing has been done, but there's some missing
> bits. It basically kinda works for the average case, but more advanced
> uses of the bootloader still have sharp pointy edges on them, the
> extent of the pointy edges is unknown. At this point the rebasing of
> the branch is non-trivial due to the merge conflicts that have crept
> in. They don't look awful, but when I tried to use git to rebase to a
> more modern FreeBSD, there were lots of stupid things. Maybe I'll try
> again...
>
> Warner



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