efix86_nap.c File Reference

iPXE CPU sleeping API for EFI More...

#include <ipxe/nap.h>
#include <ipxe/efi/efi.h>

Go to the source code of this file.

Functions
	FILE_LICENCE (GPL2_OR_LATER_OR_UBDL)
static void	efix86_cpu_nap (void)
	Sleep until next interrupt. More...
	PROVIDE_NAP (efix86, cpu_nap, efix86_cpu_nap)

Detailed Description

iPXE CPU sleeping API for EFI

Definition in file efix86_nap.c.

Function Documentation

FILE_LICENCE()

FILE_LICENCE

(

GPL2_OR_LATER_OR_UBDL

)

efix86_cpu_nap()

static void efix86_cpu_nap ( void  )

static

Sleep until next interrupt.

Definition at line 39 of file efix86_nap.c.

                                    {
        /*
         * I can't find any EFI API that allows us to put the CPU to
         * sleep.  The CpuSleep() function is defined in CpuLib.h, but
         * isn't part of any exposed protocol so we have no way to
         * call it.
         *
         * The EFI shell doesn't seem to bother sleeping the CPU; it
         * just sits there idly burning power.
         *
         * If a shutdown is in progess, there may be nothing to
         * generate an interrupt since the timer is disabled in the
         * first step of ExitBootServices().
         */
        if ( ! efi_shutdown_in_progress )
                __asm__ __volatile__ ( "hlt" );
}

References __asm__(), __volatile__(), and efi_shutdown_in_progress.

PROVIDE_NAP()

PROVIDE_NAP	(	efix86	,
		cpu_nap	,
		efix86_cpu_nap
	)