Add support for VBE simple, which permits firmware update of a single
image stored in MMC or another block device.

Signed-off-by: Simon Glass <sjg@chromium.org>

Create a new bootmeth for VBE along with a library to handle finding the
VBE methods.

Signed-off-by: Simon Glass <sjg@chromium.org>

This was a work-around for the fact that global bootmeths such as EFI
bootmgr and VBE don't use a particular bootdev, or at least select it
themselves so that we don't need to scan all bootdevs when using that
bootmeth.

Drop the system bootdev entirely.

Signed-off-by: Simon Glass <sjg@chromium.org>

Remove the dependency on CMD_PXE from BOOTMETH_DISTRO by introducing a
new hidden kconfig symbol to control whether pxe_utils is compiled,
allowing bootstd's distro method to be compiled without needing
networking support enabled.

Signed-off-by: John Keeping <john@metanate.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Correct build errors when CMD_BOOTM is not enabled:
Signed-off-by: Simon Glass <sjg@chromium.org>

Add a bootmeth driver which handles distro boot from a disk via a U-Boot
script, so we can boot a bootflow using this commonly used mechanism. This
is required by Armbian, for example.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add a bootmeth driver for sandbox, used for testing.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add a bootmeth driver which handles EFI boot manager, using EFI_LOADER.

In effect, this provides the same functionality as the 'bootefi bootmgr'
command and shares the same code. But the interface into it is via a
bootmeth, so it does not require any special scripts, etc.

For now this requires the 'bootefi' command be enabled. Future work may
tidy this up so that it can be used without CONFIG_CMDLINE being enabled.

Signed-off-by: Simon Glass <sjg@chromium.org>

Some boot methods don't act on a single bootdev but instead do their own
thing. An example is EFI bootmgr which scan various devices using its own
logic. Add a bootdev to handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add a bootmeth driver which handles EFI boot, using EFI_LOADER.

In effect, this provides the same functionality as the 'bootefi' command
and shares the same code. But the interface into it is via a bootmeth,
so it does not require any special scripts, etc.

For now this requires the 'bootefi' command be enabled. Future work may
tidy this up so that it can be used without CONFIG_CMDLINE being enabled.

There was much discussion about whether this is needed, but it seems
that it is, at least for now.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add a bootmeth driver which handles distro boot from a network device, so
we can boot a bootflow using this commonly used mechanism.

In effect, this provides the same functionality as the 'pxe' command
and shares the same code. But the interface into it is via a bootmeth.

For now this requires the 'pxe' command be enabled. Future work may tidy
this up so that it can be used without CONFIG_CMDLINE being enabled.

Signed-off-by: Simon Glass <sjg@chromium.org>