tree e2123610aa0e33e879c0b523ca23c4474d7b9545
parent fa83887e48f196cfa303ce6de32acf1dfec7cad9
author Jeremy Compostella <jeremy.compostella@intel.com> 1669932471 -0700
committer Martin L Roth <gaumless@gmail.com> 1671310298 +0000

lib: Hook up libhwbase in romstage

It's hidden behind the configuration option `CONFIG_ROMSTAGE_LIBHWBASE'.

This also adds some glue code to use the coreboot console for debug
output and our monotonic timer framework as timer backend.

Running Ada code in romstage and more particular libhwbase brings a few
challenges as global initialized variables are not supported in
Cache-As-Ram mode.

1. The libhwbase dynamic mmio driver implementation makes the Gnat
   compiler generate some global initialized variables.

   For this reason, when compiled for romstage or for romstage and
   ramstage the static mmio driver is enforced (`HWBASE_STATIC_MMIO').

2. The Gnat compiler generates elaboration functions to initialize
   program data at runtime. These elaboration functions are called by
   the romstage_adainit() function.

   The data references symbols suffixed by `_E'. Even though these
   symbols, at compilation time, do not contain any data and are
   filled with zeros, the Gnat compiler installs them in the .data
   section.

   Since these symbols are actually filled with zeros, it is safe to
   install them in the .bss section.

   cf. https://docs.adacore.com/gnat_ugn-docs/html/gnat_ugn/gnat_ugn/elaboration_order_handling_in_gnat.html#elaboration-code

This patch requires the libhwbase
https://review.coreboot.org/c/libhwbase/+/69854 CL.

BUG=b:252792591
BRANCH=firmware-brya-14505.B
TEST=libhwbae compiles for romstage and loads successfully

Change-Id: I670249d33506e886a683e55d1589cb2bf9b16aa3
Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/70275
Reviewed-by: Boris Mittelberg <bmbm@google.com>
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Reviewed-by: Tarun Tuli <taruntuli@google.com>
Reviewed-by: Zhixing Ma <zhixing.ma@intel.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>