7f8afe0631
Certain chipsets don't have a memory-mapped boot media so their code execution for stages prior to DRAM initialization is backed by SRAM or cache-as-ram. The postcar stage/phase handles the cache-as-ram situation where in order to tear down cache-as-ram one needs to be executing out of a backing store that isn't transient. By current definition, cache-as-ram is volatile and tearing it down leads to its contents disappearing. Therefore provide a shim layer, postcar, that's loaded into memory and executed which does 2 things: 1. Tears down cache-as-ram with a chipset helper function. 2. Loads and runs ramstage. Because those 2 things are executed out of ram there's no issue of the code's backing store while executing the code that tears down cache-as-ram. The current implementation makes no assumption regarding cacheability of the DRAM itself. If the chipset code wishes to cache DRAM for loading of the postcar stage/phase then it's also up to the chipset to handle any coherency issues pertaining to cache-as-ram destruction. Change-Id: Ia58efdadd0b48f20cfe7de2f49ab462306c3a19b Signed-off-by: Aaron Durbin <adurbin@chromium.org> Reviewed-on: https://review.coreboot.org/14140 Tested-by: build bot (Jenkins) Reviewed-by: Patrick Georgi <pgeorgi@google.com> Reviewed-by: Furquan Shaikh <furquan@google.com> |
||
|---|---|---|
| .. | ||
| Kconfig | ||
| Makefile.inc | ||
| console.c | ||
| die.c | ||
| early_print.c | ||
| init.c | ||
| post.c | ||
| printk.c | ||
| vsprintf.c | ||
| vtxprintf.c | ||