Linux determines its console based on several sources:
1. the console command line parameter
2. device tree (e.g. /chosen/stdout-path)
3. various other board- and arch-specific sources
If the console parameter specifies a real console (e.g. ttyS0) then that is
used as /dev/console. However, if it does not specify a real console (e.g.
ttyDoesntExist) then *nothing* will be used as /dev/console.
Reading/writing it will return ENODEV. Additionally, no other source will
be used as a console source.
Linux commit ab4af56ae250 ("printk/console: Allow to disable console output
by using console="" or console=null") recently changed the semantics of the
parameter. Previously, specifying console="" would be treated like
specifying some other bad console. This commit changed things so that it
added /dev/ttynull as a console (if available). However, it also allows
for other console sources. If the device tree specifies a console (such as
if U-Boot and Linux share a device tree), then it will be used in addition
to /dev/ttynull. This can result in a non-silent console.
To avoid this, explicitly set ttynull as the console. This will disable
other console sources. If CONFIG_NULL_TTY is disabled, then this will have
the same behavior as in the past (no output, and writing /dev/console
returns ENODEV).
[1] and [2] have additional background on this kernel change.
[1] https://lore.kernel.org/all/20201006025935.GA597@jagdpanzerIV.localdomain/
[2] https://lore.kernel.org/all/20201111135450.11214-1-pmladek@suse.com/
Signed-off-by: Sean Anderson <sean.anderson@seco.com>
At present we use the linker list directly. This is not very friendly, so
add a helpful macro instead. This will also allow us to change the naming
later without updating this code.
Signed-off-by: Simon Glass <sjg@chromium.org>
Move this out of the common header and include it only where needed. In
a number of cases this requires adding "struct udevice;" to avoid adding
another large header or in other cases replacing / adding missing header
files that had been pulled in, very indirectly. Finally, we have a few
cases where we did not need to include <asm/global_data.h> at all, so
remove that include.
Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Rini <trini@konsulko.com>
In some cases it is necessary to pass parameters to Linux so that it will
boot correctly. For example, the rootdev parameter is often used to
specify the root device. However the root device may change depending on
whence U-Boot loads the kernel. At present it is necessary to build up
the command line by adding device strings to it one by one.
It is often more convenient to provide a template for bootargs, with
U-Boot doing the substitution from other environment variables.
Add a way to substitute strings in the bootargs variable. This allows
things like "rootdev=${rootdev}" to be used in bootargs, with the
${rootdev} substitution providing the UUID of the root device.
For example, to substitute the GUID of the kernel partition:
setenv bootargs "console=/dev/ttyS0 rootdev=${uuid}/PARTNROFF=1
kern_guid=${uuid}"
part uuid mmc 2:2 uuid
bootm
This is particularly useful when the command line from another place. For
example, Chrome OS stores the command line next to the kernel itself. It
depends on the kernel version being used as well as the hardware features,
so it is extremely difficult to devise a U-Boot script that works on all
boards and kernel versions. With this feature, the command line can be
read from disk and used directly, with a few substitutions set up.
Signed-off-by: Simon Glass <sjg@chromium.org>
At present we only support updating the 'bootargs' environment
variable. Add another function to update a buffer instead. This will
allow zimage to use this feature.
Also add a lot more tests to cover various cases.
Signed-off-by: Simon Glass <sjg@chromium.org>
At present only one transformation is supported: making the Linux console
silent. To prepare for adding more, convert the boolean parameter into a
flag value.
Signed-off-by: Simon Glass <sjg@chromium.org>
This function will soon do more than just handle the 'silent linux'
feature. As a first step, update it to take a boolean parameter,
indicating whether or not the processing is required.
Signed-off-by: Simon Glass <sjg@chromium.org>
We want to add more processing to this function. Before doing so, rename
it to bootm_process_cmdline_env(), which is more generic.
Signed-off-by: Simon Glass <sjg@chromium.org>
At present this function fails silently on error. Update it to produce
an error code. Report this error to the user and abort the boot, since it
likely will prevent a successful start.
No tests are added at this stage, since additional refactoring is taking
place in subsequent patches.
Signed-off-by: Simon Glass <sjg@chromium.org>
This function currently has no tests. Export it so that we can implement
a simple test on sandbox. Use IS_ENABLED() to remove the unused code,
instead #ifdef.
Signed-off-by: Simon Glass <sjg@chromium.org>
