Popping my initramfs cherry

Jul 17, 2006 / 0 comments

I've compiled my own kernels for as long as I can remember. I do so for almost any box I use, rather than running distro supplied kernels. I think this dates back to to the days when that was just what you did, but it also ties in with the fact I often want to run the latest and greatest (eg for laptop device hardware support).

One of the things I've always avoided is the initrd. I've never really seen the point; I compile my root device driver into the kernel and thus it all works. I've seen some suggestions that the in kernel RAID array detection code isn't really being maintained and that in the future it'll require userland tools to configure a RAID array, so I've been a bit worried that I'll eventually have to learn about initrds.

In fact, that day came this weekend. My large IDE disk is dying and I decided I needed something to replace it so I could have a proper poke. So I bought a pair of SATA disks and found a cheap Highpoint RocketRaid 1520 (don't buy one of these; I mistakenly thought they were better than the good old SI 3112, but they're not. And if anyone knows of a cheap (sub £30) SATA-II PCI card then let me know. I don't think they exist.)

The RocketRaid is basically just a HPT372A (hpt366 driver in Linux) with software RAID on top. Previously I've ignored such things and just used the normal Linux RAID support, but I thought I'd give this a try with the aid of dmraid. This can read several different ATARAID formats and uses device-mapper to map the drives appropriately to keep Linux happy.

So, I install dmraid and it happily finds the RAID array and configures it all up (though I end up with the wonderfully named /dev/mapper/hpt37x_dabhghbgeg which is a bit unwiedly). All good. Except, of course, that I have to run some userland to get the RAID array up, which means I need an initrd to sort it all out if I want / on it. And I do.

These days I want initramfs rather than initrd (and I needed to remember to set CONFIG_BLK_DEV_INITRD=y in my kernel config as it's needed for initramfs or an initrd). I found the initramfs-tools package and installed it, then had a poke around for info on getting dmraid working with it. Debian bug #367661 discusses such things and I've attached the patch I used from Ubuntu to the bug report.

Then I did, as root, update-initramfs -k 2.6.17.6 -c -v and it magically created a /boot/initrd.img-2.6.17.6. Passed that as the initrd in grub and it all magically works; dmraid fires up from the initramfs, the kernel gets to mount the RAID partition as / (and the other partitions as swap and lvm) and it's all good.

Except the fact one of the disks seems to have been damaged in transit and eBuyer are being slow about issuing an RMA number. Oh, and the fact the RocketRaid sucks and only seems to get 15MB/s or so. Meh. The initramfs stuff is all happy though, and a lot easier than I expected.

Hey! Foxy!

Jul 17, 2006 / 0 comments

HDTV's not quite there yet.

Jul 13, 2006 / 0 comments

I need a new TV. I've have my current one for 6 years now and it was secondhand when I bought it. Plus it gets this little green patch now and then (which it's been doing for a couple of years). Not hugely annoying, but everything helps in justifying a new one.

My current TV is a normal 25" 4:3 set. I've worked out that if I go widescreen I need a 31" set to get the same height, which seems perfectly doable. The tricky bit comes in that I'd like HD, as hopefully the new TV will last me at least as long as the old one has. HD's only recently been launched in the UK - Sky brought out their HD service just in time for the World Cup (though I understand lots of people who'd pre-ordered didn't receive their upgrades in time). Telewest also have a recent HD service. Of course NTL, who I have, don't yet (despite them having merged with Telewest) and the Freeview DVB-T trials are only in Central London. Anyway, I won't have HD signal for a while, but I want to be ready when for when I do (and I'll be hooking a media PC up to the screen anyway, so will be able to take advantage of it via that method).

Sky appear to have decided on using 2 HD formats; 720i (1280x720, progressive) and 1080i (1920x1080, interlaced). So having support for those would be nice. In addition I'd like 1080p (1920x1080, progressive), for things like the media box and in case content becomes available in that format (HD-DVD/BluRay?). This doesn't seem like a huge request. Lots of TVs in the UK are marketed as HD Ready. What does that mean?

Essentially it specifies that the minimum native resolution of the screen is 720 lines and that there is a digital (DVI or HDMI) input that can support 720p and 1080i input and copy protection (HDCP). There is no minimum width; the set is allowed to scale the image to fit whatever it has. I've seen HD Ready sets that have a 1024x1080i native resolution - not wide enough for a native 720p image let alone 1080i. However most HD Ready sets seem to do 1366x768 as the native res, so fine for 720p but not 1080i/p. sigh

I managed to find a TV from Philips, the 37PF9830/10, which does native 1920x1080p. Amazon even sell it, though for an eye watering £2,248.28. What does this get you? Integrated Freeview decoder? No. MPEG2/4 playing of movies from flash media? No, just image viewing. A nice big monitor for your computer? No, Philips' website only lists 1024x768 as the max computer res and I've seen reports in forums that 1366x768 is possible, but no higher. There's a 42PF9830/10 (42") that adds movie playing and ethernet, which sounds good but adds who knows how much to the price (I couldn't easily find a UK price). Plus it's probably too large for me even if it was affordable.

My naive hope is that with the Sky push lots of people will have got sorted for the World Cup, or will go HD for Christmas. Meaning that come the new year I might have a better available choice of proper HDTVs and the pricing might be sane. I can dream, right?

Nothing impressive about Coke Zero

Jul 12, 2006 / 0 comments

I tried Coke Zero for the first (and probably last) time this evening. While the first mouthful actually tasted not bad, the familiar and unpleasant taste of artificial sweetener soon hit. Oh well. Much better than Diet Coke, but not something I'd buy again.

Not that I'm that fussed. I don't drink a lot of soft drinks - we buy pure juice for the house and although I occasionally drink Coke (or preferably Pepsi) when I'm out, it's only if I'm not drinking. I prefer ice cold water but it's usually ridiculously expensive and doesn't come in pints (tap water will sometimes do, but often isn't cold enough). Nice try Coke, but count me out.

Dynamic DNS implementations all insecure?

Jul 4, 2006 / 0 comments

Black Cat got another query today about offering dynamic DNS to customers. We've had people ask us about it in the past, but the DNS changes we made a while back means it's something that is possibly easier for us to offer now. So I had a think about authentication and tying it in to our current DNS interface and bits like that and decided it might not actually be too hard to get a basic service running.

Then I went and had a look at current implementations. In particular I wanted to see about client support. So I grabbed ez-ipudate, which is used on at least the Netgear DG834G and Linksys WAG54G routers. It supports a load of different services. And the only one that protects the password is GnuDIP. Various services offer HTTPS updates, but ez-ipupdate doesn't support it that I could tell.

I stopped looking at that point. If one of the most common clients doesn't care about protecting users then I don't want to depress myself by finding out how many others don't either. It's a real shame though, as it means if we want to implement dynamic DNS that'll work with standard clients we have to add another authentication system that is unique to that service.

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