Hi,
Assuming I didn't forget to commit anything -- and there were quite a
lot of small fixes that went into various places -- you can now run
NetBSD PCI device drivers in userspace on Linux.
http://repo.rumpkernel.org/pci-userspace-linux
The most obvious use case is driver development. So if we're talking
about NetBSD driver development, why support running on Linux? That's
because Linux readily provided a framework for accessing PCI devices
from userspace. I'm sure e.g. NetBSD could be supported, but that would
require investing a few days in developing a kernel module to expose a
generic PCI device to userspace.
A less obvious use case is one of those newfangled "userspace makes it
fast" thingies which are popular especially for networking. Some
adjustments would be needed for that, though, especially for handling
interrupts.
Anyway, driver iteration is nice and fast and panics are not a problem.
Probing a device takes a fraction of a second. See (*) for an example
run.
It's also quite safe even without one of the fabled IOMMU's, at least as
long as you don't misprogram addresses; even though I did misprogram
several times during development, my host is completely fin32$(@*!!@.
*)
root@watou:~/src/pci-userspace-linux/examples/if_wm# time ./example
Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005,
2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014
The NetBSD Foundation, Inc. All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
The Regents of the University of California. All rights reserved.
NetBSD 6.99.40 (RUMP-ROAST) #0: Tue Apr 15 14:33:21 UTC 2014
pooka@watou:/home/pooka/src/buildrump.sh/obj/lib/librump
total memory = unlimited (host limit)
timecounter: Timecounters tick every 10.000 msec
timecounter: Timecounter "rumpclk" frequency 100 Hz quality 0
cpu0 at thinair0: rump virtual cpu
cpu1 at thinair0: rump virtual cpu
root file system type: rumpfs
mainbus0 (root)
pci0 at mainbus0 bus 0
pci0: memory space enabled, rd/line, rd/mult, wr/inv ok
wm0 at pci0 dev 0 function 0: 82801I mobile (AMT) LAN Controller (rev. 0x03)
wm0: WARNING: unable to map I/O space
wm0: interrupting at pausebreak
wm0: PCI-Express bus
wm0: FLASH
wm0: Ethernet address xx:xx:xx:xx:xx:xx
ukphy0 at wm0 phy 2: OUI 0x000ac2, model 0x000b, rev. 1
ukphy0: 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, 1000baseT,
1000baseT-FDX, auto
panic: just a fun demo panic I added to the end of wm_attach
rump kernel halting...
halted
Aborted (core dumped)
real 0m0.678s
user 0m0.016s
sys 0m0.495s
root@watou:~/src/pci-userspace-linux/examples/if_wm#
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