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Date:      Wed, 01 Mar 2017 10:49:12 -0700
From:      Ian Lepore <ian@freebsd.org>
To:        Saurav Sachidanand <sauravsachidanand@gmail.com>, Alan Somers <asomers@freebsd.org>
Cc:        "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Allan Jude <allanjude@freebsd.org>
Subject:   Re: [GSoC 2017] Original proposal: Port kernel Lua to FreeBSD
Message-ID:  <1488390552.60166.23.camel@freebsd.org>
In-Reply-To: <CACKq%2BiWgtgExz51H9RvzJ3ze8qMD2X9Lw%2Bmi4Cbi5ue3vGGqjA@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> <CACKq%2BiVMd0edbOpg2Hr1bDdFmwekqt78YiCWbaY-iC16gqOW5g@mail.gmail.com> <CAOtMX2hSTpJmL81NKJVWRUZ=vq66uKTUW0VCSx9-oaqkQ7mpzw@mail.gmail.com> <CACKq%2BiWgtgExz51H9RvzJ3ze8qMD2X9Lw%2Bmi4Cbi5ue3vGGqjA@mail.gmail.com>

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The thought of python being any part of the base system is nothing less
than horrifying.  Didn't we learn our lesson with perl all those years
ago?

-- Ian

On Wed, 2017-03-01 at 23:18 +0530, Saurav Sachidanand wrote:
> Since the language(s) to be included are chosen at compile time
> it wouldn't be forcing anyone to use a bloated bootloader.
> Wouldn't Python's richer standard library (eg: re) be useful in
> certain situations?
> 
> On Wed, Mar 1, 2017 at 9:42 PM, Alan Somers <asomers@freebsd.org>
> wrote:
> > 
> > Python is huge, and we already have people complaining that the
> > bootloader doesn't fit in their boot partitions ever since it
> > gained
> > GELI support.  The advantage of Lua is that the embedded
> > interpreter
> > is very small.  I'd rather not bloat the bootloader too much.
> > 
> > -Alan
> > 
> > On Wed, Mar 1, 2017 at 9:08 AM, Saurav Sachidanand
> > <sauravsachidanand@gmail.com> wrote:
> > > 
> > > 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@fr
> > > > > > > eebsd.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/externa
> > > > > > > > > l/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/m
> > > > > > > > > aster/sbin
> > > > > > > > > /luactl
> > > > > > > > > [7] - http://netbsd.gw.com/cgi-bin/man-cgi?lua+4+NetB
> > > > > > > > > SD-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-ha
> > > > > > > > > ckers
> > > > > > > > > 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
> > > _______________________________________________
> > > freebsd-hackers@freebsd.org mailing list
> > > https://lists.freebsd.org/mailman/listinfo/freebsd-hackers
> > > To unsubscribe, send any mail to "freebsd-hackers-unsubscribe@fre
> > > ebsd.org"
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