PnP BIOS for x86 is part of drivers, so I missed it in the initial GDT page alignment patch. Kudos to Andrew for fixing that. Unfortunately, fixing the build introduced a kernel panic when trying to setup the as of yet unallocated GDTs for the APs. I totally misdiagnosed this. The problem happens only when NR_CPUS > physical CPUs. Fix is to ignore missing GDT's. Signed-off-by: Zachary Amsden Index: linux-2.6.14-rc2/drivers/pnp/pnpbios/bioscalls.c =================================================================== --- linux-2.6.14-rc2.orig/drivers/pnp/pnpbios/bioscalls.c 2005-09-28 15:57:42.000000000 -0700 +++ linux-2.6.14-rc2/drivers/pnp/pnpbios/bioscalls.c 2005-09-28 15:59:37.000000000 -0700 @@ -537,6 +537,8 @@ void pnpbios_calls_init(union pnp_bios_i _set_limit((char *)&bad_bios_desc, 4095 - (0x40 << 4)); for(i=0; i < NR_CPUS; i++) { + if (!get_cpu_gdt_table(i)) + continue; Q2_SET_SEL(i, PNP_CS32, &pnp_bios_callfunc, 64 * 1024); Q_SET_SEL(i, PNP_CS16, header->fields.pm16cseg, 64 * 1024); Q_SET_SEL(i, PNP_DS, header->fields.pm16dseg, 64 * 1024);