An old bug in AMD’s Athlon family of chips may still be snaring Linux users.

Affected users will need to be running a 2.4 kernel, an AGP and an Athlon or Duron CPU. At cause is a compatibility issue with Intel’s 4MB page size. (x86 processors have used 4k pages, ever since paging was introduced in the 80386).

AMD issued a patch for Windows users (http://www.amd.com/products/cpg/athlon-duron/amd_win2k_patch.html) in Fall 2000, with an accompanying PDF (http://www.amd.com/products/cpg/athlon/techdocs/pdf/tn17.pdf) [13k].

But all the patch is, is a one-line registry change, described here (http://support.microsoft.com/default.aspx?scid=kb;EN-US;q270715), that only disables the expanded page size. And not all Pentium-specific instructions.

For Linux users, it's a one line workaround, too. Pass the line “append mem=nopentium” at boot time (via your boot loader of choice), to disable all Pentium specific instructions.

French distro Gentoo (http://www.gentoo.org) reported this yesterday, and found itself Slashdotted into the netherworld. It's still down, as we write. ®