Changes from v1: - Make CONFIG_CSM a top-level build target in parallel with COREBOOT/QEMU. - More Kconfig cleanup. - Add generic find_pmtimer() function to find the pmtimer from ACPI tables. - Make Xen and coreboot builds both use find_pmtimer(). - Merge E820 table one entry at a time instead of wholesale copy. - Add pic_save_mask() and pic_restore_mask() functions. - Less intrusive size reduction for handle_post(). - Various other cleanups.