ATAng just in case

Matt Dillon posted that if the recent ATAng integration keeps your IDE controller from working (though the opposite is more common), do:

#define NO_ATANG in /usr/src/sys/dev/disk/ata/ata-all.h

Propolice at least

Tomaz Borstnar noted that propolice support is still there for GCC2 (the only compiler at the time it was added) but not yet for GCC3. Matt Dillon followed up saying that other ‘gcc3isms’ have to be cleaned up first, though integration shouldn’t be hard.

SATA support, sorta

Matt Dillon’s added experimental support for the Silicon Image 3512 SATA controller.

Incidentally, credit goes to David Rhodus for generating the base patch for all the ATAng work committed by Matt Dillon yesterday.

ATAng added

Matt Dillon has brought in ATAng from FreeBSD 4 except for “the dma chipset changes and the busdma changes”, while retaining the apparently better DragonFly MPIPE version.

Spamfilters on

Spam filters have been turned on for the various DragonFly lists: (Taken from Matt Dillon’s post explaining this)

  • Matches against certain really annoying viruses
  • With a MIME Content-Type header of text/html
  • With a MIME Content-Type header of multipart/alternative
  • Without a working reverse DNS lookup
  • Without a FQDN formatted HELO line
  • With an invalid envelope sender. The spam filter does a realtime
    connect back to the SMTP server associated with the envelope sender
    and attempts to RCPT to it. If this fails the mail will be rejected.

Threading thread

There’s been a slight conversation about threading, where Jeroen Ruigrok van der Werven mentioned he would want hybrid, or M:N threading. Miguel Mendez chimed in that 1:1 threading, while not as spiffy, is easier to implement and Sten Spans posted a link to this PDF describing 1:1 threading in Linux. (I assume – haven’t read it yet) Matt Dillon brought up a larger issue: asynchronous syscall messaging support is needed before any of this thread work can be done.

More mount

Joerg Sonnenberger committed a change to mount that allows you to specify mounting options when doing ‘mount -a. Chris Pressey put it together from FreeBSD code.

Token epiphany

Matt Dillon was answering a question from Bosko Milekic that caused him to have a realization on how to improve token-handling in both single and multiple CPU situations, with apparently significant performance benefits. I’m pasting his post to .kernel here:

“Not entirely. First, please note that the current token implementation does not work very well… it’s a mess to use because cpu #B can steal away cpu #A’s token by sending cpu #A an IPI message requesting the token. This means cpu #A has to be in a critical section to ‘protect’ the token, and must re-acquire the token (in case it was lost) after it blocks.

After thinking about this quite a bit I have come up with a solution that, in a moment of enlightment, would make our tokens operate like self-contained little RCU implementations (superior to Linux’s implementation, in fact!).

I intend to fix our tokens by not allowing an IPI to steal a token until the owning cpu has gone through a thread switch, or by explicit release. This means that, once fixed, our token implementation will allow us to abstract RCU-like operations, which I think is very important. It is not what I originally intended tokens to be but it is turning out to be what they should be.

The nice thing about the revamp I intend to do on the token code is that the RCU abstraction will wind up being a lot better then Linux’s RCU abstraction, because it will be compartmentalized. Only cpus competing for the same token are effected rather then all cpus in the system. We would not have the serialization problem that Linux has.”