It seems libata was broken in 2.6.24 for pegasos. Take a look at https://bugzilla.redhat.com/show_bug.cgi?id=430802 for more informations and for the fix (http://patchwork.ozlabs.org/linuxppc/patchcontent?id=16281)
Steps to Reproduce:
The commit for the patch referenced in comment #1 is located here:
This is included in vanilla-sources-2.6.25_rc2.
I was able to patch gentoo-sources-2.6.24-r2 and compile it.
Can you patch your own gentoo-sources-2.6.24-r2 and test the fix. Upon a successful test we can backport into the next release of gentoo-sources for the 2.6.24 kernel.
Fixed in genpatches-2.6.24-4 (gentoo-sources-2.6.24-r3), thanks for bringing this to our attention