Fwd: Making MPSAFE/Converting Wi-Fi driver (GSoC)

[Jeandre Kruger <jeandreckruger%gmail.com@localhost>]

Hi,

I submitted these proposals for GSoC 2022.  They were turned down, so
I apologize for not getting back in contact sooner.  I'd like to know
if I should resubmit either or both, and what, if anything, I could do
to improve them?  (In the meantime, bge(4) was made MPSAFE, so it
should be omitted; the non-standard form factor PSU which I'd need for
the computer that had that controller is out of stock, anyway.  Of
course, the timeline would need updating also.)

Thanks in advance,
Jeandre

---------- Forwarded message ---------
From: Jeandre Kruger <jeandreckruger%gmail.com@localhost>
Date: Sat, Apr 16, 2022 at 11:39 PM
Subject: Re: Making MPSAFE/Converting Wi-Fi driver (GSoC)
To: Martin Husemann <martin%duskware.de@localhost>


On Thu, Apr 14, 2022 at 9:33 PM Martin Husemann <martin%duskware.de@localhost> wrote:
> The work to be done is very different for ethernet and wifi drivers,
> so I would not mix both in one proposal. You could offer two proposals,
> one for bge(4) and [if time permits] alc(4), the other for athn(4) and
> [if time permits] ath(4).

Taking that suggestion, here are my draft proposals.  I'll appreciate
any feedback.  (I put the Ethernet drivers the other way around,
because alc(4) will be easier hardware-wise, but either way should be
possible.)

Update Atheros Wi-Fi driver(s) for new Wi-Fi stack

SUMMARY

The NetBSD Project has been working to adapt the FreeBSD Wi-Fi stack.
When this is complete, things will be more up-to-date, and NetBSD will
let one use multiple Virtual Access Points with the same Wi-Fi
adapter.  As of yet, most of the Wi-Fi drivers need to be converted to
the new stack.  The athn(4) driver will be reworked as necessary, and
if time permits the ath(4) driver also.

DELIVERABLES

When complete, these devices will be usable on the "wifi" Mercurial
topic with the new stack.

IMPLEMENTATION

This should be straightforward.  Among other things the driver will
need to be changed to use fine-grained locking instead of the big
kernel lock.  The existing converted drivers can serve for reference.

My netbook has an Atheros 9285 Wi-Fi adapter.  The default (preferred)
driver is athn(4), but it also works with the ath(4) driver, which
supports a somewhat different set of Wi-Fi adapters.

Previous discussion:
http://mail-index.netbsd.org/tech-net/2022/04/13/msg008184.html

SCHEDULE

May 20-June 12 (UTC)

Familiarize self with driver, necessary interfaces, & differences in
new Wi-Fi stack.  Study in detail:

https://wiki.netbsd.org/Testing_new_wifi/
https://wiki.netbsd.org/Converting_drivers_to_the_new_wifi_stack/

Begin coding a bit – dev/pci/if_athn_pci.c and dev/ic/athn.c

Ascertain any possible problems, or necessary tasks not here
mentioned, with help of mentor.

June 13-June 27

Official start of coding.  At least the most trivial changes of those
outlined in wiki article should be made in athn(4).

June 27-September 12

Finish reworking and testing athn(4) as necessary.

If athn(4) is completed soon enough, update the ath(4) driver analogously.

September 12 End of coding

Make Ethernet drivers MPSAFE: alc(4), possibly bge(4)

SUMMARY

The NetBSD network stack presently requires the big kernel lock to be
held, limiting performance with multiple processor cores.  The alc(4)
driver, for a range of Atheros Ethernet interfaces, will be reworked
so as not to need the protection of the big kernel lock; and if
possible and time permits, the bge(4) driver also, for Broadcom
Gigabit interfaces.

DELIVERABLES

When completed the drivers will allow for greater performance with
networking on SMP systems (provided the NET_MPSAFE kernel option is
enabled).  Such Atheros Ethernet interfaces appear to be common, so
hopefully this will be of some benefit to many NetBSD users.

(Implementation as detailed in schedule.  I have access to more than
one device with an Atheros Ethernet adapter, and a computer which
shouldn't be hard to fix with a Broadcom Gigabit integrated
controller.)

SCHEDULE

May 20-June 12 (UTC)

Familiarize self with structure of alc(4) driver, Ethernet, and
relevant NetBSD interfaces, as necessary.  Study doc/TODO.smpnet and
dev/pci/if_alc.c.

Use existing MPSAFE drivers for reference.  Determine what needs to be
protected by mutexes.

June 13-September 12

Rework and test alc(4) as much as necessary.  If alc(4) is completed
soon enough, begin work on bge(4) and convert it analogously.

BIOGRAPHY

Since beginning programming with Scratch at age 7 in 2011, I've gained
some practice with various programming languages, including C and x86
assembly.  I've written some small personal projects – if I don't just
abandon them, they aren't usually very practical, but I learn
something nevertheless.

Trying out ancient UNIX and VAX BSDs on SimH was fun, although now it
has been shown that ancient UNIX probably can't be redistributed
outside the US.  I've found operating systems fascinating for most of
my life – since before I began programming – and would be enthusiastic
to help improve one.

This is a simple game I wrote with C and SDL2:
https://ldjam.com/events/ludum-dare/40/pet-overload

The most recent thing I've programmed is a basic RISC-V M-mode
emulator in Scratch – not capable of running NetBSD or any operating
system, but it runs several small C and assembly programs, including a
game and a simple Scheme interpreter:
https://github.com/Jonathan50/scratch-risc-v-programs

Contact: Email or on #netbsd-code