Older blog entries for richdawe (starting at number 61)

slamb:

Another interesting thing I learnt at work a couple of weeks ago is that Linux does not support non-blocking I/O for disk files.

I've been trying to work out if I should surprised at that or not. I wonder how hard it would be to implement in the kernel. I also wonder whether non-blocking I/O on disk files would actually hurt performance compared with blocking I/O - I guess that depends on the number of processes and mix of I/O.

cvs over ssh loses data?

I've been following a thread on the bug-gnulib mailing list about fixing cvs over ssh so that it doesn't lose data. Well, I was surprised that this happens, but it reminded of a couple of times at work where cvs diff -pu3 2>&1 | less seemed to be missing bits of diffs. It turns out that it's an old problem.

Note that this problem isn't specific to cvs. It will affect anything where ssh inherits stderr. See Ian Lance Taylor's explanation in the thread linked above.

I'm telling everyone I know, because I found this quite surprising. No-one has said "yeah, didn't you know that" yet, so I'm guessing this isn't widely known, unless it's one of those things that beardy people know about.

Music

"Giving Up The Ghost" by DJ Shadow

Upgraded to Fedora Core 2

Well, I've now entered 2004 by upgrading from RedHat 8.0 to Fedora Core 2. The upgrade was mostly smooth in the sense that I still have a system that works. Lots of things broke, however. I guess most of this is due to upgrading from RH 7.2, through 7.3 and then 8.0.

Here's what I had to do:

  1. Uninstall the wreakage of linuxconf - I think this is from RH 7.x. The FC2 installer barfed on this, when trying to check the status of the linuxconf installer.

  2. Rebuild sitecopy from sources. I use this to upload my web pages. Packages can be found at my shiny new Fedora Core 2 rpm area.

  3. Upgrade PPTP software using the instructions from the PPTP client FC2 HOWTO.

  4. ipchains-restore seems to barf on the old-format that RH8.0 used. (Did RH8.0 use ipchains-save? I can't remember.) So I tried firewall-config from the Start^WGNOME menu, but it barfed. It turns out that firewall-config is a crusty left-over, so removed that. system-config-securitylevel is the configuration program now. (I think it was called lokkit-<something> on RH8.0.) I didn't have any complicated firewall rules, so that did the job.

  5. RH8.0 used LPRng. FC2 uses CUPS. So I ran the printer configurator. There's now support for my printer (yay!), an HP DJ5150. But the configurator could not create the printer queue. That seemed a bit odd. I ran strace and ltrace ont he configurator and it turned out that it was still referencing LPRng via /etc/alternatives. The configurator was trying to update alternatives, but it failed for some reason. So I ran "alternatives --config printer", selected CUPS (the only option), reran the configurator and it worked.

Given that I've only been running FC2 for 8 hours, I'm sure there are some more surprises around the corner.

Music

"Twice Round" by the Guardians of Dalliance

Life

I haven't really had any time to do any Free Software hacking recently. It's not looking hopeful for the near future. I want to polish up auto2rpm a bit and finally get subscripto to do something useful.

I moved house, which went pretty smoothly. 2 weeks without Internet - how did I survive? My ADSL router's power supply did die just after I got ADSL back again, which was a bummer. One new power supply from Maplin and I had my ADSL back. Yay for Maplin's customer service. Maplin is like Fry's, but much smaller scale and more expensive.

Work has also been manic and probably will be for a month or so. Hopefully it'll settle down then, so I can actually think about what needs doing long-term. I'm stuck in the "get it done" state, which sucks. My coffee consumption has gone through the roof, which isn't a good sign (faster, damn you, faster!).

Edinburgh Festival(s)

I went to Edinburgh Fringe Festival last week, which was excellent, although I now have no money. I went with a friend from uni and one of his mates. We saw quite a lot of comedy: improv, a bit of stand-up, a spoof play ("Bad Play 2: Worser Play", which was hilarious), a musical and a bunch of other stuff I probably forgot. If you're up there, I recommend going to the free improv at the Stand Comedy Club on York Place at lunch (12:30-13:30) - their show in the evening is also excellent and well worth the money.

One conscious decision was to avoid everything that had any mention of Dubya or Iraq - I've had more than enough that to last me a lifetime. It's not like they can say anything particularly new.

I also spent some time at the Book Festival. I tried not to see too much, because Cheltenham has a literature festival in October. I liked Taras Grescoe's talk on his travel book about the people he met while travelling - probably because I love travelling. The other talks (on ethics in politics and on dying languages) were not quite as interesting. The one on dying languages was basically hijacked by the host, which ruined it for me.

I also saw "Super Size Me" at the Film Festival, which made me feel really hungry (not for a burger, though!).

I lost count of how many festivals there are in Edinburgh in August - at least five! I didn't see anything at the International or Jazz Festivals, for instance.

Music

"Zillion Dollar Gravy" by London Elektricity

subscripto

I've done some hacking on subscripto, my mailing list subscription manager. I fixed a whole raft of bugs in the parsing of GNU Mailman status messages (translation: it now works ;) ).

subscripto now does something useful: If you tell it which addresses are dead/alive, it can filter out those subscriptions which are dead/alive. So now you can see which lists need the address switching.

I haven't released this version yet. Hopefully I'll do a bit more hacking on it today.

subscripto still doesn't do what I originally intended it to do: automating the subscription/unsubscription/changing of address. One day soon it will...

auto2rpm

A guy at work asked if there was an equivalent to cpan2rpm for packages using the autotools (autoconf, automake, libtool). AFAIK there wasn't, so I wrote one: auto2rpm.

auto2rpm is still in its early days of "release early, release often" (translation: there aren't many features), but it should do the job. It relies on packages using GNU automake - you need to build a tarball using "make dist". After that, it will do the rest, leaving you with some nice shiny rpms.

Spammy moderation messages

slamb: Good point about blocking mail purporting to be from your domain, if it's not from localhost or an authenticated sender. So I wonder why gnu.org doesn't do that.

It occurred to me after posting that the idea of publishing valid mailing list addresses for a domain is really just a specific instance of publishing a directory of valid recipients for that domain. That is, of course, a really bad idea, since it saves spammers the effort of trying to do dictionary attacks.

Music

Lemon D remix of "Whiplash" by Future Cut

GNU Mailman, moderation messages and some other ramblings

One thing I've noticed on a number of GNU mailing lists is that time to time a mail appears saying "you're message is awaiting moderation". The original message had a From of, say, libtool@gnu.org. The moderation message comes from, say, mailutils-admin@gnu.org.

This is really stupid. No-one should be able to send mail from the list address. That should be a one-way address.

Likewise, why would anyone send mail from the admin address? Sure, they could set Reply-To, if they want to distribute the admin task.

So I wonder why GNU Mailman doesn't just discard these kind of mails and save everyone's time and bandwidth.

Incidentally I know some lists set the Reply-To to the list, but the From will still be the original.

I wonder if we could take this a little further and have some mailing list "authentication" protocol. This would be a variant of SPF (Sender Permitted From, now Sender Policy Framework). You'd put a record in DNS which indicated which mailing lists were valid and would also include the admin addresses. Then mailing list A could check whether the traffic was from mailing list B's admin or mailing list address and discard as bogus.

To be honest, this is small fry. I wish I could disable the virus alerts my ISP keeps sending me (90% of my mail). I'm just not interested (like I care someone sent me a virus - what's new?). Most of the viruses are sent to a mailing list I run at Yahoo Groups for one of my former projects. Interestingly some of the bogus From addresses are harvested from the manual for that project.

I guess I should just switch the mailing list to a member's only list. That kind of grates with the spirit of open source, even if the project is dead. Hey ho.

Music

General Midi mix of "Reformatted" by Sonic Infusion

Outlook & Mail Headers

deekayen: It's been a while since I used Outlook, but I think you can see the full headers by clicking the "Edit" menu then "Options" and then I think there's some obvious thing you click (perhaps it's called "Full headers" or something). I feel your pain - I'm an Evolution user in a sea of Outlook users.

Another thing that's hard to do with Outlook is get the actual full raw text of a mail. As far as I can tell, it's virtually impossible. One work-around is to use Evolution to extract the mail from Exchange using IMAP. That is, in fact, the only way I know of exporting folders from Exchange without handing over a big wodge of cash to someone.

3 May 2004 (updated 3 May 2004 at 16:50 UTC) »

Traffic Cones

Apparently they're going to make robotic traffic cones. That sounds like a good idea, since it can't be safe laying out the cones on a motorway. I'm hoping they'll still have the speed and lane restriction signs up and won't do it while the traffic is flowing at its usual speed.

But what happens when the cones turn...evil?

Music

"Illicit Groove" by JMJ & Richie from "Storm from the East" off Moving Shadow - mellow d'n'b

1 May 2004 (updated 1 May 2004 at 10:28 UTC) »

CPUs and Power Consumption

I've wondered from time to time why low-power CPUs aren't used more in desktops. I wouldn't exactly describe myself as an environmentalist, but if you told me I could have, say, 75% of the peformance at 50% of the power consumption if I bought the lower power-consumption version of a CPU, then I'd go for it. But you don't see desktop PCs offered in low power versions, generally.

OpenBSD

One interesting thing I noticed when reading the OpenBSD 3.5 release notes was this:

OpenSSL now directly uses the new AES instructions some VIA C3 processors provide, increasing AES to 780MBytes/second (so you get to see a fan-less cpu performing AES more than 10x faster than the fastest cpu currently sold).

It sounds like a VIA C3 box plus OpenBSD would make an awesome VPN gateway.

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