[U-Boot] [PATCH 67/72] serial: Unconditionally enable CONFIG_SERIAL_MULTI

[Stephen Warren]

On 09/29/2012 03:53 PM, Marek Vasut wrote:
> Enable CONFIG_SERIAL_MULTI for all builds of U-Boot. That includes
> both SPL builds and non-SPL builds, everything. To avoid poluting
> this patch with removal of ifdef-endif constructions containing
> CONFIG_SERIAL_MULTI, the CONFIG_SERIAL_MULTI is temporarily added
> into CPPFLAGS in config.mk . This will be again removed in following
> patch.

Marek,

This patch (at least, the version of it checked into u-boot/next) breaks
U-Boot on Tegra.

I believe the reason is because nothing ever calls serial_initialize()
in the SPL on Tegra. If I edit arch/arm/cpu/arm720t/tegra20/spl.c
function preloader_console_init() to call serial_initialize() right
before it calls serial_init(), then everything works fine. Without this,
drivers/serial/serial.c is never initialised (not even BSS cleared!) and
so it's left set to some bogus value, and so get_current() doesn't
replace it with default_serial_console(), so an invalid pointer is
accessed, causing a hang or crash.

I'm not sure quite what the correct solution is here. Is Tegra's custom
spl.c doing too much; stuff that should come from the common spl.c is
cut/paste here? Or, is adding the call to serial_initialize() the
correct fix? Or, is the root-cause of the problem that BSS
(serial_current) isn't being cleared to 0?

Thanks for any pointers.