src/arch/i386/prefix/kkkpxeprefix.S

/*****************************************************************************
 * PXE prefix that keeps the whole PXE stack present and provides an exit hook
 *
 * This prefix is essentially intended solely for the case of ipxelinux.0
 *****************************************************************************
 */

FILE_LICENCE ( GPL2_OR_LATER )

/* Since we have the whole stack, we can use cached DHCP information */
REQUIRE_OBJECT ( pxeparent_dhcp )

/* Provide the PXENV_FILE_EXIT_HOOK API call */
REQUIRE_OBJECT ( pxe_exit_hook )

#define PXELOADER_KEEP_UNDI
#define PXELOADER_KEEP_PXE
#define _pxe_start _kkkpxe_start
#include "pxeprefix.S"
[pxe] Provide PXENV_FILE_EXIT_HOOK only for ipxelinux.0 builds PXENV_FILE_EXIT_HOOK is designed to allow ipxelinux.0 to unload both the iPXE and pxelinux components without affecting the underlying PXE stack. Unfortunately, it causes unexpected behaviour in other situations, such as when loading a non-embedded pxelinux.0 via undionly.kpxe. For example: PXE ROM -> undionly.kpxe -> pxelinux.0 -> chain.c32 to boot hd0 would cause control to return to iPXE instead of booting from the hard disk. In some cases, this would result in a harmless but confusing "No more network devices" message; in other cases stranger things would happen, such as being returned to the iPXE shell prompt. The fundamental problem is that when pxelinux detects PXENV_FILE_EXIT_HOOK, it may attempt to specify an exit hook and then exit back to iPXE, assuming that iPXE will in turn exit cleanly via the specified exit hook. This is not a valid assumption in the general case, since the action of exiting back to iPXE does not directly cause iPXE to exit itself. (In the specific case of ipxelinux.0, this will work since the embedded script exits as soon as pxelinux.0 exits.) Fix the unexpected behaviour in the non-ipxelinux.0 cases by including support for PXENV_FILE_EXIT_HOOK only when using a new .kkkpxe format. The ipxelinux.0 build process should therefore now use undionly.kkkpxe instead of undionly.kkpxe. Signed-off-by: Michael Brown <mcb30@ipxe.org> 2011-12-11 02:11:45 +00:00			`/*****************************************************************************`
			`* PXE prefix that keeps the whole PXE stack present and provides an exit hook`
			`*`
			`* This prefix is essentially intended solely for the case of ipxelinux.0`
			`*****************************************************************************`
			`*/`

			`FILE_LICENCE ( GPL2_OR_LATER )`

			`/* Since we have the whole stack, we can use cached DHCP information */`
			`REQUIRE_OBJECT ( pxeparent_dhcp )`

			`/* Provide the PXENV_FILE_EXIT_HOOK API call */`
			`REQUIRE_OBJECT ( pxe_exit_hook )`

			`#define PXELOADER_KEEP_UNDI`
			`#define PXELOADER_KEEP_PXE`
			`#define _pxe_start _kkkpxe_start`
			`#include "pxeprefix.S"`