I'll be involved in the video team again.
posted at: 03:14 | path: / | permanent link to this entry
As previously announced elsewhere, video recordings from the Distribution Developer Rooms at FOSDEM 10 are now available. All but two talks were recorded and are available in Ogg Theora+Vorbis format, in low-bandwidth (~300 kbit/s) and high-bandwidth (~1.5 Mbit/s) versions.
These recordings should also be available later on the FOSDEM YouTube channel.
Video and audio were recorded by Dominique Dumont (H.1302) and the DebConf video team (H.1308) with the assistance of some additional volunteers. Thanks to everyone involved in recording, and thanks also to the speakers and the organisers of FOSDEM.
posted at: 20:17 | path: / | permanent link to this entry
As some people noticed, a driver update to support a major hardware release in my day job and a long series of trivial patches motivated by Debian kernel work combined to make me joint most prolific change author for Linux 2.6.33. This was a fluke, and 2.6.34 is likely to be fairly quiet for me.
Meanwhile the kernel team is still working hard on fixing bugs in Linux 2.6.32. As previously announced, this kernel version will be used in both Debian 6.0 'squeeze' and Ubuntu 10.04 LTS. It is also known to be the kernel version for RHEL 6 though this has not been officially announced. If you find a serious bug that was fixed in 2.6.33 or later, please ask the author to send the fix to stable@kernel.org so that it will be included in all these distributions. Note that this happens automatically for commits with the line 'Cc: stable@kernel.org' in their description.
We are also continuing to backport new drivers and new hardware support in existing drivers into Debian 5.0 'lenny' (stable). Missing support for common hardware is considered an important bug and suitable for stable updates. However, if there were major changes to a driver before those that added new hardware support, we may be unable to produce a backport. We are not able to carry out comprehensive hardware testing and do not want to risk a regression existing hardware support.
Finally, a major change I have been working on is the transition from the old IDE drivers for PATA controllers to new drivers based on libata. The old IDE subsystem is no longer developed and some drivers do not properly support all the hardware that their libata-based counterparts do. However, while the IDE drivers generate device names beginning with 'hd', libata presents PATA devices as SCSI devices and generates device names beginning with 'sd'. In a system that already has other SCSI or SCSI-like disks, names may change somewhat unpredictably. Similar problems exist for PATA CD/DVD and tape devices.
So, while the transition doesn't involve any kernel hacking, it does require a complex upgrade process. Any configuration files that refer to IDE or SCSI device names may need to be changed. It is not enough to switch to only SCSI device names, since we cannot know what they are in advance and the configuration files should continue to work with kernel versions from before and after the transition. In the case of disks we can normally use the partition label or UUID: many tools understand the LABEL= and UUID= syntax, and for others we can refer to the symlinks under /dev/disk created by udev. In the case of CD/DVD devices, we can use the aliases /dev/cdrom etc. created by udev. In the case of tape devices, however, you're on your own.
In experimental, kernel image packages depend on a new package linux-base which implements this transition (from 2.6.33-1~experimental.2; the previous version was broken). The postinst script will prompt you to make changes automatically or manually. It can convert most bootloader configuration files, /etc/fstab, the udev CD aliases configuration and the initramfs-tools resume partition. It can also label partitions that don't have a label or UUID. Please do test it and verify that its changes are correct. All changed configuration files are backed up with a suffix of '.old' (or '^old' in one case).
posted at: 18:11 | path: / | permanent link to this entry
Most of the Debian kernel team members are attending the Linux Plumbers Conference in Portland over the next 3 days. We'll be discussing kernel packaging and integration issues among ourselves and with upstream and other distributors.~
You may have noticed that Linux 2.6.31 is out but not yet in sid. This kernel version contains a large number of known regressions which should be fixed in subsequent stable updates, so we will wait for those. In the mean time we've uploaded an update to 2.6.30 which should resolve the most serious bugs.
posted at: 18:34 | path: / | permanent link to this entry
Low-bandwidth versions of the recorded talks are now available. There are currently two exceptions:
While the master versions of all these talks have been checked, not all the generated low-bandwidth versions have. Please let us know on debconf-video@lists.debconf.org if there is something wrong with them other than the following:
The high-bandwidth versions will be uploaded over the next week (slow connection is slow).
posted at: 14:14 | path: / | permanent link to this entry
Several people have been asking after the videos. My answer to them is "we release when it's ready".
Seriously, though, I'm sorry about the delay in publishing videos. There was some miscommunication between me and the sysadmin team at DebConf which meant I couldn't take files away with me then. Peter Palfrader reassembled the video RAID later, copied the necessary files onto a single hard disk, and posted that to me. This disk apparently got lost on the way, but eventually arrived here last week after a 3-week journey.
Over the weekend I dealt with most of the videos that required editing, and today I was able to resume the transcoding process. Tomorrow I intend to start uploading again.
posted at: 04:24 | path: / | permanent link to this entry
posted at: 12:43 | path: / | permanent link to this entry
posted at: 00:12 | path: / | permanent link to this entry
A question from AJ reminded me that I haven't said much about the changes to packaging of firmware in Debian, and in particular the separation of non-free firmware from the Linux kernel.
There is an ongoing process upstream to move firmware blobs from drivers into a firmware/ subdirectory of the source, which is now almost complete. Since most of this firmware is non-free, we remove it from the source tarballs for kernel packages but use it to update the firmware-nonfree "source" package.
We continue to patch some drivers to separate out firmware, and have been submitting our changes upstream. Most of these have been accepted though the DRI drivers matrox, r128 and radeon are notable exceptions.
A few months ago I attempted to make a new inventory of the remaining firmware blobs outside of the firmware/ subdirectory. I identified three that should still be addressed. The Linux-libre project, however, removes many other constant arrays from the kernel (and disables the affected drivers) where I judged the array to be a plausible preferred form of modification.
Much of the non-free firmware removed from the kernel is now available in the firmware-linux package in the non-free section of the Debian archive. Starting with Linux 2.6.31, we will build the DFSG-free firmware shipped with Linux into a package called firmware-linux-free, which will be recommended by kernel image packages. The contents of firmware-linux will be moved to firmware-linux-nonfree and firmware-linux becomes a meta-package depending on the other two packages.
Many other firmware images never distributed with Linux are also packaged for the benefit of users that require them.
posted at: 17:23 | path: / | permanent link to this entry
One of the more interesting talks at last week's PyCon was on the new Python licence.
posted at: 02:51 | path: / | permanent link to this entry
This week I'm at PyCon in Chicago, helping to train and supervise the A/V team in recording the tutorials and talks. We have a lot of inexperienced volunteers but they're learning quickly. Carl Karsten (in charge of A/V) and Ryan Verner (another outsider with long experience from LCA) are organising things. Ryan, Dave Noble and I provide technical assistance to the rest of the team.
I'm also working on my first Django app, which will be used for reviewing files. This is essentially a clone of the excellent work done by Gunnar Wolf and Damian Viano in Pentabarf. PyCon doesn't have a centralised database so this is a standalone application. Ryan is now applying styles to my horribly bare HTML, and I have a short list of bugs to fix before we ask the video team to start reviewing.
The tutorials started yesterday and talks wil start tomorrow in different rooms, so we have to set up all the equipment again and reconfigure for multiple cameras. Hopefully by Saturday things will be running smoothly and I can spend some time in the city. It would be a shame to come all this way and stay by the airport for the entire time!
posted at: 18:58 | path: / | permanent link to this entry
I'm going to 
Carl Karsten of the PyCon organisers recruited three of us from the DebConf video team to lead and train the video team at PyCon.
posted at: 17:44 | path: / | permanent link to this entry
Jérémy Bobbio suggested that I should explain how I looked for packages affected by a compiler bug (Debian bug 506713; gcc bug 38287). I don't claim that this is a particularly good way to do it, but here it is:
First, I identified a pattern to search for. Unfortunately I don't really understand the cause or fix for the bug, but I did have the example which led to this bug report: Debian bug 490999. The bad code was a stack-pointer-relative load immediately after a stack allocation (SPARC save instruction) where the offset was not adjusted for the stack allocation:
I generalised this to:save %sp, -112, %sp ld [ %sp + 0x40 ], %i5
save %sp, offset1, sp ... ld [ %sp + offset2 ], register
where offset1 + offset2 < 0. Of course, this may
be valid if the intervening instructions include a restore,
branch or store to the effective stack location that the last instruction
loads from. I ended up allowing up to 10 intervening instructions and
examining a disassembly to work out which cases were valid.
I looked up the instruction encoding for these two instructions. Thankfully SPARC is RISC so they are simple and regular:
save %sp, offset1, sp is encoded as 0x9de3a000 | offset1 & 0x1fffld [ %sp + offset2 ], register is encoded as 0xc003a000 | reg << 25 | offset2 & 0x1fff
I took the dumb but effective approach of scanning entire files for this pattern rather than only scanning their code sections. This seemed to work - I got no false hits for non-code - but might not work for other patterns that could match ASCII text.
I wrote the scanning program in Python, which is my default choice of
language unless I know it's going to be too slow. I was hoping to be able
to read the code files into arrays, but unfortunately the Python array
type only supports the native byte-order (SPARC is big-endian and I was
intending to use an x86 which is little-endian). I tried reading into a
tuple using struct.unpack, which does support explicit byte-ordering, but
this used so much memory for larger files that the program swapped to a
crawl. So finally I resorted to reading the file into a string, doing a
string search for '\x9d\xe3', rejecting matches that weren't appropriately
aligned, then unpacking and comparing the code words from the point of the
string match.
(In Python 3.0 I would have to use the bytes type for this,
as str is a Unicode string type.)
So that's how I scanned single files. The next step was to find, unpack
and scan all the SPARC shared libraries in the archive. (This particular
code generation bug is understood to affect only PIC code, and that is
normally only used in shared libraries.) I wrote functions to search
Contents-sparc for shared library files - assumed to match the pattern
([^\s]*/lib[^/\s]+\.so(?:\.[^/\s]*)?) - and to parse
Packages to find the filenames for the packages containing those files.
The latter uses the debian_bundle.deb822 module from
python-debian.
The last key function downloads and unpacks a package using
wget and dpkg-deb. I could have used
the httplib module for downloading but I correctly
anticipated that I'd need to restart the script several times so I
wanted to cache the packages which was easier to do using
wget.
So, that's the explanation. If you really want to see it, here's the code.
posted at: 00:53 | path: / | permanent link to this entry
posted at: 02:26 | path: / | permanent link to this entry
I finally got sufficiently fed up with Subversion yesterday to begin converting my package repositories to Git. This has many benefits, including the fact that I can now easily publish them. Browse or clone them as you prefer. Or just ignore them.
posted at: 15:50 | path: / | permanent link to this entry
Some drivers in Linux include "firmware" - code that runs on the device the driver deals with, not the main processors in the system. Most of this is in a binary or equivalent form, which is probably not the form that it was originally written in. This makes it non-free by Debian's standards, an issue which has led to much argument around previous releases and has blown up once again.
The good news is that kernel developers are making a continuing effort to separate this from the driver code. I've collected together the patches that do this and written 2 of my own, which appear to cover all the remaining sourceless firmware. But I was only able to test one of these drivers (radeon) - the rest is up to you.
| Driver | Hardware which requires firmware | Bug report | Change made |
|---|---|---|---|
| cassini | Sun "Cassini" Ethernet controllers with "Neptune" PHY | 498631 | removed |
| dabusb | BayCom DAB-USB radio receivers | 502663 | moved to firmware-dabusb |
| e100 | Intel PRO/100 Ethernet controllers with PCI revision 8, 9, 15 or 16 or built into ICH6 or ICH7 (LAN-on-motherboard) | 494308 | moved to firmware-e100 |
| kaweth | Kawasaki LSI USB Ethernet controllers | 502665 | removed |
| mga | Matrox G200, G400, G450(?) and G550 graphics controllers, 3D acceleration only | 502666 | moved to firmware-matrox |
| qla1280 | QLogic QLA1XXX SCSI controllers | 502667 | moved to firmware-qlogic |
| r128 | ATI Rage 128 graphics controllers, 3D acceleration only | 494007 | moved to firmware-ati |
| starfire | Adaptec DuraLAN aka Starfire Ethernet controllers | 501152 | moved to firmware-adaptec |
| tehuti | Tehuti Ethernet controllers | 501153 | moved to firmware-tehuti |
| typhoon | 3Com Typhoon (3CR990) Ethernet controllers | 502669 | moved to firmware-3com |
| whiteheat | ConnectTech WhiteHEAT USB serial adapters | 502668 | removed |
Do you depend on the drivers for which I have removed the firmware? Do you have contacts with the vendors who might be able to help relicence it? Please send mail to the bug report.
I checked my email and found a response from ConnectTech; the WhiteHEAT firmware will probably be clear to package in firmware-nonfree. There is no need for anyone else to contact them.
posted at: 01:53 | path: / | permanent link to this entry
I discovered an interesting "feature" of chmod(1), which caused a package build to fail. According to the GNU manual page, if no letters are used before a "-" or "+", "the effect is as if a were given, but bits that are set in the umask are not affected." The command will also fail with an error message when it does this!
The Single Unix Specification says this is correct, though there is some ambiguity over whether the exit status should be 0 or not.
Anyway, the result is that it is generally a bad idea to call chmod in this way in a script. Always specify who the permission changes should apply to.
posted at: 23:24 | path: / | permanent link to this entry
In addition to live streams, recordings of each event should be published on meetings-archive.debian.net. There is an RSS feed of these, which should work nicely in Miro: http://meetings-archive.debian.net/pub/debian-meetings/2008/debconf8/index.rss. That feed is also included on Planet Debian. This is the first time I've tried generating RSS so apologies in advance if I make a mess of the Planet.
posted at: 09:32 | path: / | permanent link to this entry
Sorry, I missed a few last time.
| Dependency-based boot sequence | low | high |
| Data-mining Popcon | low | high |
| Debian-installer - an update | low | high |
| Wacky ideas II | low | high |
posted at: 20:58 | path: / | permanent link to this entry
A few of the recordings from DebConf 7 had to be recovered in whole or in part from tape. For personal and technical reasons, a few of these were not done last year, and I have finally dealt with them now. The last few sessions are:
| The secure Debian Desktop | low | high |
| Debian - The Universal Operating System? | low | high |
| Wacky ideas BoF | low | high |
| lintian BoF | low | high |
| Debian travels around the world | low | high |
| Leading a Free Software project | low | high |
| Method diffusion in large volunteer projects | low | high |
| Debtags is ready | low | high |
| OpenStreetMap | low | high |
| Maintaining packages with Git | low | high |
| netconf | low | high |
| Time for a better init system | low | high |
Hopefully these are useful to someone. Sorry it took so long!
posted at: 10:15 | path: / | permanent link to this entry
After a fair amount of clean-up, a lot of waiting for review, and some ruthless pruning, I and my colleagues at Solarflare finally got our net driver accepted for Linux 2.6.26. Meanwhile a larger version of the driver made it into Xen's Linux tree, along with dependent drivers to provide a secure fast path to the hardware from domU. Somewhere down the road we're going to have to resolve these two versions, but now I'm just pleased to have a working driver in-tree.
There are some other changes I've worked on over the past few months:
However, this is still only part of my work. My main task at the moment is to write more unit tests for our next NIC.
posted at: 16:15 | path: / | permanent link to this entry
I'm employed at Solarflare Communications in the test group, supporting the work of testers and developers by developing test frameworks. (We actually have very few pure testers and a whole lot of automation.). In a major break from my previous jobs, I've been working mostly in Python on applications for use in-house.
More recently I've become involved in maintenance of our network driver for Linux, starting with updating it to use current kernel coding conventions, and submitting for inclusion in the kernel. This has become a bit frustrating because while there are a lot of people prepared to run checkpatch and pick nits, there are not so many who will do a thorough review of a driver that's 20,000-odd lines long. And without someone doing that, it won't go in.
Meanwhile some of my colleagues have done some great work to accelerate Linux networking on Xen by having drivers in dom0 and domU cooperate to expose hardware resources directly to domU. Our hardware architecture supports many virtual NICs with their own packet queues and set of buffers, so this does not compromise the security of the physical machine and dom0. The results are very impressive.
The original motivation for the virtual NIC architecture was as a basis for a user-level networking stack, which can provide very low latency and reduced CPU usage. This software was originally proprietary but has now been released under GPLv2 as OpenOnload. Google invited two of my senior colleagues to talk about this - here's a video of their talk about user-level networking.
posted at: 00:24 | path: / | permanent link to this entry
posted at: 22:44 | path: / | permanent link to this entry
posted at: 03:43 | path: / | permanent link to this entry
As threatened promised, I have produced a renamed
version of Ion3 that should avoid upstream trademark claims and thus be
DFSG-compliant. Some translations are out-of-date, but I'll release a first
version now and try to get those updated later. The new name is ParticleMan.
When I put
the name to a vote some time back the winner was Iceparticle, but there's
already an icewm and I couldn't resist the
TMBG reference.
(Whoever suggested this name to me: I had already thought of it but forgot to
include it in the poll.)
The packages are in my repository for now.
posted at: 18:22 | path: / | permanent link to this entry
Since ries (ftp-master.debian.org) is still down, I've uploaded packages for the latest version of Ion3 to my own server. That's:
deb http://womble.decadent.org.uk/debian/ sid/ deb-src http://womble.decadent.org.uk/debian/ sid/
The repository is signed with my personal key.
posted at: 01:49 | path: / | permanent link to this entry
The DebConf 7 videos needed some post-processing, mostly to recover missing pieces from tape. I've done a large part of that, but it's not yet complete.
The video team to-do list has details of the recordings that still need work, and the sessions that we believe were not recorded. Please tell us if we did record some of these, and we will have another look through our tapes for them.
The conversion to "publication" formats (i.e. small enough to offer for download) was started at the conference and I have continued this at home over the past 2 weeks. Unfortunately this has been interrupted by some hardware failures. It looks like the CPUs in two of my PCs were running hot enough to be damaged (slowly) but not hot enough to trigger an alarm or automatic shutdown. The remaining conversions will be running mostly on my laptop, which is pretty fast and should be able to finish conversion of the recordings that are in a good state in about 2 days. However, some of the converted files may be broken and need some manual attention.
My upload bandwidth is only 448 kbit/s so the high-quality files will take about a week to upload.
As ever, the video files are being published on meetings-archive.debian.net.
posted at: 18:39 | path: / | permanent link to this entry
Not my title, but that of Peter Gutmann's presentation about PKI, specifically X.509 as used in SSL. It's informative, entertaining, and I suspect not as well known as it should be.
posted at: 23:43 | path: / | permanent link to this entry
Ion3 supports docked applications and is compatible with the docking protocols used by WindowMaker and KDE. Normally you would use:
dopath("mod_dock")to load mod_dock, which provides a standard corner dock, toggled using MOD1+D.
However, recent versions also support docking applications in the status bar, in "system tray" style:
-- In cfg_ion.lua:
defwinprop {
class = "foo-window-class",
statusbar = "foo"
}
-- In cfg_statusbar.lua:
mod_statusbar.create {
...
template="... %systray_foo"
}GNOME unfortunately uses a different dock protocol. However, the docker program can adapt from this to the WindowMaker protocol. So you can include a GNOME system tray in your status bar by including docker in your X session and this in your Ion3 configuration:
-- In cfg_ion.lua:
defwinprop {
class = "Docker",
statusbar = "dock"
}
-- In cfg_statusbar.lua:
mod_statusbar.create {
...
template="... %systray_dock"
}posted at: 23:39 | path: / | permanent link to this entry
It's day 2 of DebConf and dvswitch is being used by many members of the video team. So I have a pretty good idea of what it does well and what I need to fix in it.
The most serious problem is that there's no way to start and stop recording from the GUI. That's actually controlled by starting and stopping the file sink, which runs on a remote machine. Here I have arranged to start it by running a command with ssh in the background, which is stopped by quitting dvswitch or with pkill! The result is that we can record a lot of junk between events, which has to be checked and then discarded, or alternately stop recording and risk missing the next event.
Also, we like to number our cameras: 1 for the speaker, 2 for the audience, 3 for slides. But dvswitch assigns numbers to sources in order of connection. I fudged around this by again using ssh to start the sources in the proper order after dvswitch.
Despite these and a number of other flaws, it seems that several people have been impressed by the ability to cover talks from multiple angles. I hope this will attract more people to contribute to dvswitch so that it can serve DebConf and other conferences better.
posted at: 02:09 | path: / | permanent link to this entry
The DebConf video team is using a large number of programs, some common and some of our own, spread across 20-30 computers. Some may be interested to know what this is.
Most of the custom software and configurations should be included in the debconf-video project on Alioth.
posted at: 02:07 | path: / | permanent link to this entry
Semi-annoying, semi-amusing:
I'm using Firefox Iceweasel 2.0.
posted at: 00:36 | path: / | permanent link to this entry
Continuing a trend of upstream control-freakery, the author of Ion has claimed Ion and Ion3 as trademarks and set out a trademark policy that will require Debian to rename it. I've created a poll for selecting a new name.
posted at: 13:55 | path: / | permanent link to this entry
I just released version 0.5.0 of dvswitch, the software DV mixer intended for use at DebConf 7. I believe I've met all of the video team's essential requirements and most of the desirables.
Unfortunately real video mixing seems to take a faster machine than I have at the moment and I very much doubt I'll have time to improve that much. Although I have implemented picture-in-picture mixing, it won't be usable and may result in frame dropping, so I've started a stable branch intended for DebConf 7 that doesn't include it. Version 0.5.0 is released from this branch and can be considered the first alpha test version. There's now a little over a month to test, fix bugs and make minor improvements on this branch.
posted at: 09:28 | path: / | permanent link to this entry
I've been meaning to attend the ACCU Conference for some years and finally decided to pay my own way for a couple of days this year. It was an opportunity to hear world experts on C++ and other programming topics and to a smaller extent to meet and socialise with other professional programmers.
I attended the following sessions:
This was a somewhat surprising choice of speaker and subject since I think most attendees work on proprietary software, but I think any sensible developer in the proprietary world will try to build on free libraries under non-copyleft licences, where appropriate. Mark talked about governance and leadership in "open source" projects (actually praising Debian for having a clear constitution) and about the need for good communication between projects, for example about release schedules. He seems to have accepted that Launchpad cannot be a single hub, and called for standard formats for, for example, exchanging information about related bugs between bug trackers. But it doesn't sound like he's ready to take the lead on that.
Andrei looked at the strengths and weaknesses of various error reporting mechanisms in C++ and introduced a technique for making error handling more flexible. Normally a function is designed either to indicate errors through its return value or to throw an exception on error. If a function returns an error indicator, it's easy for callers to ignore it. If it throws an exception on error, then a caller that provokes errors more often than the called function's author anticipated pays a high cost in processing time for those errors.
Andrei's solution involves a class template
Likely<typename T> whose instances hold either a
return value of type T or an exception. A function that
can fail has a specialisation of this template as its return type.
The caller can check for failure if it knows how to handle it, or it
can ignore it - in which case the conversion to T or the
destructor will throw the exception. This is clever but doesn't seem
to be entirely satisfactory. The destructor which throws does first
check that no exception is already being processed, avoiding collision
of the two exceptions and consequent abrupt termination of the
program, but this can result in errors being unexpectedly ignored.
A marathon 3-hour talk on designing and testing software, particularly C++ programs (the subject of his well-known book) as a set of well-defined components.
Lakos first defined these components as being "physical" i.e. sets of source files - normally a header file defining an interface, an implementation file, and a test driver file. They may also include metadata for the build system. He talked about the value of reusable components (as if this wasn't obvious!) and the risk of introducing circular dependencies - which essentially turn many components into one and reduce reusability - if we fail to keep track of dependencies. Software built out of components can be viewed as a hierarchy or stack defined by dependencies. In a large system, components with similar dependencies and dependents can be grouped together into packages or package groups to simplify a view of these dependencies.
He explained that the test driver's dependencies count just as much as the implementation's, because we cannot reasonably test a component until we have tested its dependencies. Test drivers should also be written to avoid depending on environmental settings and configuration, so far as possible.
Finally, and perhaps most importantly, he spent a long time talking about how to construct test cases and test data. I might try to summarise this in a later entry if anyone's interested.
Andrei began by complaining that OpenOffice Impress was even worse than PowerPoint, but being able to use Linux (specifically Ubuntu) more than made up for the pain.
He briefly presented four key ideas that he believes programmers should understand and be ready to make use of:
I think I've been convinced to write an article about standardisation of multithreading in C++.
Crowl gave an overview (similar to this) of the extensive work that's been done on standardisation of multithreading in the C++ language and library. This is one of the most important features in C++0x due to the increased parallelism mentioned above. The current semantics of multithreaded programs are not standardised, resulting in subtle but potentially serious differences between current C++ implementations that support multiple threads, and in the need for assembly-language code in programs that use lockless synchronisation. Much of this is also relevant to C and is being considered by the C standard committee.
Stroustrup recapped the 4 forms of syntax for initialising objects
in C++, some inherited from C and some necessarily invented for C++,
none of which are entirely generic. He noted the lack of a simple
syntax to initialise the elements of containers, which violates the
general principle that class types should have the same status as
built-in types in C++. He then introduced a new initialiser syntax
that he and others have defined for C++0x, which is a brace-enclosed
comma-separated list of values, similar to that used for arrays and
C-style structures (aggregates). Container types can define a
constructor with a parameter of type const
std::initializer_list<T> & and when constructed with
this new form of initialiser they will receive this wrapper for a
constant array of element values. For types that do not, the values
in the list are treated as arguments to some other constructor, if one
matches. Otherwise, for compatibility, this may be treated as
aggregate initialisation.
There was far too much information here for me to even begin to summarise. Suffice to say there are lots of good things coming bu the library committee will have its work cut out to get them all properly specified in time for the Committe Draft coming late this year.
I also met old friends and new, put faces to names from newsgroups and books, and got too little sleep.
posted at: 18:16 | path: / | permanent link to this entry
posted at: 15:19 | path: / | permanent link to this entry
Just as Gecko exposes a bug in the nv driver, it can also provoke poor performance in the ati driver. This turns out to be avoidable by configuring X to use the newer driver interface.
posted at: 01:11 | path: / | permanent link to this entry
For this year's DebConf, we (the video team) want to be able to use multiple cameras like at DebConf 5, where we had one for the projection screen and one for the presenter fed to an analogue mixer and a digitiser. At DC6 we had no mixer and no budget for one. Same at DC7 - unless we can do it with software. Toresbe had a go at writing one but didn't finish. I want to give it a go. So:
posted at: 01:18 | path: / | permanent link to this entry
This is my new blog for technical/geeky/Debian stuff. I'm keeping my LiveJournal for social and private matters and syndicating this one to Planet Debian.
I hope this separation will make me less afraid of boring LiveJournal readers with technical minutiae and Debian politics or boring Planet Debian readers with local social stuff, so I actually write more. Don't get too hopeful though.
posted at: 16:55 | path: / | permanent link to this entry