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May 04 2008

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a problem slug

I bought myself another slug recently so that I could have one dedicated to internal work and the other used for public facing webs. I wasn’t really comfortable with having my network backup and apt-get mirror on the same beast as a public web. I know from experience that public facing systems are vulnerable and I have to assume that my webcam slug is disposable.

However, it seems that I picked exactly the wrong time to build a new slug because I fell foul of a previously undocumented bug in the new initramfs-tools (version 0.92) in Debian testing. This version generated a ramdisk that made the slug unbootable. This bug was particularly irritating because it only manifested itself at the end of the complete Debian install – i.e at the point when the installer had flashed the new initramfs and rebooted. Because I had been so successful with the earlier slug only weeks before, I thought at first that either I had made a mistake, or, worse, I had bought a problem slug which I could not return having voided the warranty. So I wasted some more time reflashing first with unslung and later with the original Linksys image – just to satify myself that I had a working beast. Then I checked the debian-arm mailing list. A couple of other users reported similar problems and the cuplprit – initramfs-tools – was quickly identified and rapidly fixed (see bug #478236).

When researching the problem, I picked up a useful tip from the mail list on a quick way of backing up a working slug image which is not documented in the how-to section of the slug website. This tip enabled me to take a copy of the image from the known good working slug and flash it to the non-working new slug at the end of (yet another) complete Debian install.

On a working system, do “cat /dev/mtdblock* > backup.img”, and copy that backup image off to a safe place. Use that image with upslug2 to flash to a non-working (or corrupted) slug thus: “upslug2 -i backup.img”.

The problem I encountered is now fixed with the release of 0.92a of initramfs-tools which is now in the Lenny tree.

Permanent link to this article: http://baldric.net/2008/05/04/a-problem-slug/