Return an error when the user does not select an OS, so we know whether
to boot or not.

Move calling of bootflow_menu_run() into a separate function so we can
call it from other places.

Expand the test to cover these cases.

Add some documentation also, while we are here.

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

- Generally we just drop the #ifdef CONFIG_SYS_LONGHELP and endif lines
  and use U_BOOT_LONGHELP to declare the same variable name as before
- In a few places, either rename the variable to follow convention or
  introduce the variable as it was being done inline before.

Signed-off-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

At present 'bootflow list' shows <NULL> for the filename when it is not
present. Show an empty string instead, since that is more user-friendly.

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

Some bootflows (such as EFI and ChromiumOS) delay reading the kernel until
it is needed to boot. This saves time when scanning and avoids needing to
allocate memory for something that may never be used.

To permit reading of these files, add a new 'bootflow read' command.

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

Provide an option to dump this information if available.

Move the funciion prototype to the common x86 header. Allow the command
line to be left out since 'bootflow info' show this itself and it is
not in the correct place in memory until the kernel is actually booted.

Fix a badly aligned heading while we are here.

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

Some Linux parameters can be set automatically by U-Boot, if it knows the
device being used. For example, since U-Boot knows the serial console
being used, it can add parameters for earlycon and console.

Add support for this.

Note that this is an experimental feature and we will see how useful it
turns out to be. It is very handy for ChromeOS, since otherwise it is very
difficult to manually determine the UART address or port number,
particularly in a script.

Provide an example of how this is used with ChromeOS.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

Add a bootflow command to update the command line more easily. This allows
changing a particular parameter rather than editing a very long strings.
It is also easier to handle with scripting.

The new 'bootflow cmdline' command allows getting and setting single
parameters.

Fix up the example output while we are here, since there are a few new
items.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

On x86 boards Linux uses a block of binary data to provide information
about the command line, memory map, etc. Provide a way to store this in
the bootflow so it can be passed on to the OS.

No attempt is made to generalise the code, since other archs don't need
this information. The field is present always, though, to avoid needing
accessors or #ifdefs when building code on other archs.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

The "bootargs" environment variable is used to set the command-line
arguments to pass to the OS. Use this same mechanism with bootstd as well.
When the variable is updated, it is written to the current bootflow. When
the current bootflow is updated, the environment variable is updated too.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

Some operating systems have a command line which can be adjusted before
booting. Store this in the bootflow so it can be controlled within
U-Boot.

Fix up the example output while we are here, since there are a few new
items.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>