definitely related to toolchain change as there have been no changes to acpi part :-(I confirm, rebuilding kfreebsd-7 version 7.2-4 leads to the same problem.And using gcc-4.2 does not change the result :(
And older binutils, might be bug like #537389 ? 7.2-3 used binutils_2.19.51.20090714-1 7.2-5 used binutils_2.19.51.20090805-1 There is available some in the midle http://ftp.de.debian.org/debian/pool/main/b/binutils/binutils_2.19.51.20090723-1_kfreebsd-i386.deb Petr