"Embedded" Arch

arew264 · 2008-09-28 19:49:47

Okay, I'm rewriting this post because I went on too many tangents before.

I'm looking to run Arch on a robotics project (I can choose between x86_64 and i686 with the hardware I have in mind). Arch would be running from a CompactFlash card that the BIOS would see as an IDE hard drive.
Since this is flash memory, I'm pretty sure I would need to mount it readonly. How should I go about installing Arch to handle this? As it's technically going to be a hard drive, do I need to use ISOLinux or will Grub suffice?
Basically, should I install a base system or follow the Wiki instructions to make a LiveCD, using a partition on the CompactFlash card to store it? Should I follow some combination of the two?

This question is dependent on the answer to the last one, but how big of a CompactFlash card should I buy? How much RAM will be necessary? If I have to go the LiveCD route, I would probably make a UnionFS (or whatever it's called) of a RAMDisk and the read-only flash memory, and I would need probably around 1 GB of RAM. Is this correct?

Any advice would be greatly appreciated, I'm just not sure what I'm jumping into.

Last edited by arew264 (2008-09-29 21:58:42)

arew264 · 2008-09-30 02:16:45

Bump because I rewrote my first post. Hopefully this is legal.

rson451 · 2008-09-30 02:38:04

This would probably be a good question for lilsirecho. He's got a FaunOS running off compact flash cards I believe. If he doesn't reply you may want to ping him with an email.

jonathantan86 · 2008-09-30 09:26:12

I got ArchLinux to run off a USB flash drive using a normal hard disk install. I used unetbootin to load the Arch Linux ISO onto another USB drive (to save a CD), plugged in that one (the "CD"), booted, plugged in the second one (the "hard disk"), mounted it, and then went through the installation procedure as usual.

You need to be careful about the GRUB settings though. Since the "hard disk" USB flash drive is (1,0) at the time of the installer, the autogenerated menu.lst will have (hd1,0) entries in it. You will have to change it manually to (hd0,0) since you presumably will boot only with the "hard disk" USB.

The Arch wiki (on the ASUS EEE page or something like that) has hints on what to do when using a flash drive to reduce writes. I think using UnionFS would be a good idea but I've never tried it and I don't know how.

I used a 4GB thumb drive and 1GB RAM, but I think that less than that will suffice. In particular, you don't need so much RAM - I'm typing this on a 256MB Arch Linux laptop.

So in your case, you could adapt what I did, in which case you will treat the CompactFlash as a hard disk and not a LiveCD.

gradgrind · 2008-09-30 13:44:18

It should be easy enough to do a straight install to a flash drive (so that it boots with grub), just like to a hard drive. It will in any case not be recognised as a CD. How big the drive should be depends of course on what you want to install. You should, however, be careful about writiing to it too often, which would call for various tweaks (I suppose similarly to eeePC, etc.).

A better route might be to use an overlay file system so that (most) writes are done to RAM. The easiest way to approach this might be using larch, if your envisaged usage patterns are appropriate. Using larch it is possible to have all writing done to RAM, and then at shutdown/reboot optionally written to the flash device.

Using an uncompressed read-only base + writeable overlay (e.g. using aufs) would be an approach which would probably allow more flexible merging to the flash device, but you would have to construct such a system yourself.

arew264 · 2008-10-26 17:13:29

Yes, Larch looks like the simple solution, and I'm willing to do whatever tweaking may be necessary to get such a system working. I wasn't expecting this to be a simple installation.

If this project ever reaches fruition (which is about a 50/50 chance), I'll post up the process I follow.

lilsirecho · 2008-10-26 17:27:17

The install of faunos is straight-forward...download the USB.img and run ..dd...program to install.

It loads 600 packages in a 1GB install. Best to repartition to 2GB or more to enable added packages.

It is the simplest OS to install of any I have seen including puppy.

Unfortunately, the OS is not being upgraded, having been invaded by porno interests.

Hopefully, soon to be re-instated under a new name.

The system can be loaded now regardless with kernel 2.6.24 and performs very well...stable as a rock.

EDIT: My system uses sata to cf adapters ..only writes to overlays in aufs when save session is invoked. Best of all...it runs all in ram, very nifty speed!

Last edited by lilsirecho (2008-10-26 17:31:29)

Arch Linux

#1 2008-09-28 19:49:47

"Embedded" Arch

#2 2008-09-30 02:16:45

Re: "Embedded" Arch

#3 2008-09-30 02:38:04

Re: "Embedded" Arch

#4 2008-09-30 09:26:12

Re: "Embedded" Arch

#5 2008-09-30 13:44:18

Re: "Embedded" Arch

#6 2008-10-26 17:13:29

Re: "Embedded" Arch

#7 2008-10-26 17:27:17

Re: "Embedded" Arch

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