efix86_nap.c

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00001 /*
00002  * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
00003  *
00004  * This program is free software; you can redistribute it and/or
00005  * modify it under the terms of the GNU General Public License as
00006  * published by the Free Software Foundation; either version 2 of the
00007  * License, or any later version.
00008  *
00009  * This program is distributed in the hope that it will be useful, but
00010  * WITHOUT ANY WARRANTY; without even the implied warranty of
00011  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012  * General Public License for more details.
00013  *
00014  * You should have received a copy of the GNU General Public License
00015  * along with this program; if not, write to the Free Software
00016  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
00017  */
00018 
00019 FILE_LICENCE ( GPL2_OR_LATER );
00020 
00021 #include <gpxe/nap.h>
00022 #include <gpxe/efi/efi.h>
00023 
00024 /** @file
00025  *
00026  * gPXE CPU sleeping API for EFI
00027  *
00028  */
00029 
00030 /**
00031  * Sleep until next interrupt
00032  *
00033  */
00034 static void efix86_cpu_nap ( void ) {
00035         /*
00036          * I can't find any EFI API that allows us to put the CPU to
00037          * sleep.  The CpuSleep() function is defined in CpuLib.h, but
00038          * isn't part of any exposed protocol so we have no way to
00039          * call it.
00040          *
00041          * The EFI shell doesn't seem to bother sleeping the CPU; it
00042          * just sits there idly burning power.
00043          *
00044          */
00045         __asm__ __volatile__ ( "hlt" );
00046 }
00047 
00048 PROVIDE_NAP ( efix86, cpu_nap, efix86_cpu_nap );