Roy's Blog

A Hacker's musings on Code | Tech | Life

So finally I've moved all services from my old server to my Christmas Xen box! This was not without problems due to the fact it had to run NetBSD -current

  • gcc toolchain is broken for some packages which affected running any PHP build
  • clang toolchain was broken for my config (USE_SSP= yes and CPUFLAGS+= -march=core2)
  • clang compiles as a whole were broken due to a recent efiboot import

In hind-sight, I could have had the box up and running a lot sooner if I used NetBSD-7 guests (or maybe just a NetBSD-7 build box), but no, I just had to get -current running. It offers more than -7 and prior exerience told me that tracking -7 was very problematic ... but that could have been due to my settings and wanting to compile everything with clang. I've currently got 3 -current images there now ... the Xen DOM0, the actual server itself as Xen DomU (without any compiler or tools) and another Xen DomU which just builds stuff for other guests to use.

Anyway, the box itself is now up and running and all relevant services have been moved to it. During this move, I decided to modernise things a little and setup HTTP/2. If you're reading this then it's working :) As such, I've re-directed all basic HTTP traffic to HTTPS and it does seem to load a lot faster. One side effect of this is that I've stoped using my own self signed certificates and I'm now using the nice Let's Encrypt service. pkgsrc users should use the py-certbot package and don't bother searching for any letsencrypt package as it's been renamed. I found this quite confusing as there was no reference to the rename in pkgsrc I could find and wasted a little time on it.

But now it's live I can finally look into bringing online some other development utilities to play around with as the server has a lot more room to grow :)

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After starting the year with curses work, I decided to do some more!

Currently we lack Soft Label Key functions as specified by POSIX. What are these? Glad you asked! Soft Label Keys ripoff a line from the bottom of the screen and allow for up to 8 keys to be displayed there. You can define labels for them, colours, etc.

"BIG WHOOP!" I hear you say. "My app already does this, why should I care?"

Because SLK also works with the terminfo database to work out if the terminal natively supports labels (via plab_norm, label_on, etc)! This means a line doesn't have to be ripped off from the screen so no real-estate is lost. Sadly, no terminal actually seems to support these markings. But if one is ever made, it should work fine.

Now, not many curses apps actually use the SLK functions, probably for this very reason. But some do, and it is a standard so I've coded NetBSD to support this natively.

Sadly, this has uncovered a bug in the NetBSD curses library where cursor movement in a one line window at the bottom of the screen appears to push the window up. This is very visible with SLK and will have to be fixed for any apps that actually use it, but the SLK implementation itself is sound as resizing the terminal forces a redraw and it looks fine.

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So over the holidays, I managed to get in some good quality family time and find some time to work on some Open Source stuff. I meant to work mainly on dhcpcd, but it turned out I spent most of my time working on NetBSD curses library so that Python Curses now works with it. Now, most people reading this blog may not care much for NetBSD or for curses, but it's important because ncurses is used pretty much everywhere by default ..... aside from NetBSD. And most readers should know, I go out of my way to promote interoperable software even when it's at a detriment to my own projects. That's just how I roll.

There is a apparently a thing called PD Curses but I don't know anywhere that actually uses it by default. If you know, please email me @ roy@marples.name or . I do know that the pkgsrc curses framework supports it.

And this is the thing I'm currently doing. As NetBSD curses supports more POSIX functions (and a few ncurses extensions, sadly) more and more packages now work alongside NetBSD curses, so I'm plowing through pkgsrc again moving things to the curses framework. This is important, because there is logic in devel/ncurses to use NetBSD curses when passing certain criteria, but sadly this always brings ncurses as a possibility to be linked or it's header used, both of which are quite bad for NetBSD curses so there is a method to my madness.

One interesting thing though is that since I started comitting my curses patches, it turns out that Sabotage Linux is using NetBSD curses and made it portable. I'm chatting with one of their devs and we're starting to merge of a few of their patches back into NetBSD.

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So one of the main features of dhcpcd was the ability to add and remove addresses and subnets in accordance with interface preference and state. This worked very well in Linux, both for IPv4 and IPv6.

When I discovered FreeBSD and then NetBSD making dhcpcd work with the same features provided troublesome. For the IPv4 case, we needed to patch the kernel so that IFA_ROUTE remained sane. For the IPv6 case it was a lot more complicated as parts of the IPv6 stack rely on the kernel processing Router Advertisements instead of a 3rd party tool. Working this out was a lot more time consuming and complicated, but we got there with minimal fuss!

So as of now, dhcpcd can fully replace the NetBSD and Linux in kernel Router Advertisement handling code.

But why was I right after all these years? Because quite a few knowledgeable NetBSD folk assured me that the kernel was fine and it was likely dhcpcd at fault. As it turned out, it really was the kernels fault.

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So, I've been slowing going back to using GNOME instead of using KDE-4. I do this flip flop every once in a while as I'm never truely satisfied by either. Now, GNOME works quite happily on my Gentoo/Linux machines, but this is not the case on my favoured NetBSD ones. Or rather, parts of GNOME don't work as they should, like the Evolution mail client.

Evolution suffers two problems on my NetBSD box. One, it takes over 5 minutes to load and two, once it has checked and downloaded mail from my server it closes without error. The 2nd problem is probably a programming error in Evolution or one of its many dependencies, but the first problem could be anywhere! Research led me to this possible soltuion. If you look closely, you'll find an old post by me in that thread fixing it with ld --as-needed on Gentoo/FreeBSD, but that isn't a real solution for NetBSD / pkgsrc users. Anyway, at first glance the patch on that thread makes perfect sense. So I came up with better patches (one for glib, one for Evolution) and it now loaded in under 3 seconds! All was well :)

Well, not entirely. Other applications started to show isses as a result. So at least we know we're in the right area. I then spent a few hours wading through the Evolution build chain and came to the conclusion I still hate autotools as it obscures everything but was no better off fixing it. But I did come up with a test case that opened an evolution library and searched for a symbol that did not exist. This should 30 seconds, which is far too long and is also probably what the poster of the FreeBSD patch did in the mail thread.

Cutting to the chase, the runtime linker on NetBSD was checking the same library for the same symbol over and over again. Going back to the FreeBSD linker, they have a patch which implements a negative cache which should solve this. But it doesn't, as it doesn't cache missed weak symbols. Luckily this is easy to rectify and you can find my patch here and an updated one after performance testing elsewhere here. Now Evolution loads in under 3 seconds and crashes right away - but that's an issue to fix another day :)

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