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BACKPORT: x86: add cache-as-ram migration option

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There are some boards that do a significant amount of
work after cache-as-ram is torn down but before ramstage
is loaded. For example, using vboot to verify the ramstage
is one such operation. However, there are pieces of code
that are executed that reference global variables that
are linked in the cache-as-ram region. If those variables
are referenced after cache-as-ram is torn down then the
values observed will most likely be incorrect.

Therefore provide a Kconfig option to select cache-as-ram
migration to memory using cbmem. This option is named
CAR_MIGRATION. When enabled, the address of cache-as-ram
variables may be obtained dynamically. Additionally,
when cache-as-ram migration occurs the cache-as-ram
data region for global variables is copied into cbmem.
There are also automatic callbacks for other modules
to perform their own migration, if necessary.

BUG=chrome-os-partner:19342
BRANCH=none
TEST=Built and booted. Noted that CAR values are not read incorrectly.

Change-Id: Ie0104a6e24cc6430a575ee3691671900c36db0d9
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/51386
Reviewed-by: Stefan Reinauer <reinauer@google.com>
This commit is contained in:
Aaron Durbin 2013-05-10 00:33:32 -05:00 • committed by ChromeBot
commit 2e9e50142f
10 changed files with 168 additions and 0 deletions
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12
src/arch/x86/init/romstage.ld
View file

@ -35,6 +35,10 @@ SECTIONS
*(.rodata.*);
*(.rom.data.*);
. = ALIGN(16);
_car_migrate_start = .;
*(.car.migrate);
_car_migrate_end = .;
. = ALIGN(16);
_erom = .;
}
@ -48,8 +52,16 @@ SECTIONS
. = CONFIG_DCACHE_RAM_BASE;
.car.data . (NOLOAD) : {
_car_data_start = .;
*(.car.global_data);
/* The cbmem_console section comes last to take advantage of
* a zero-sized array to hold the memconsole contents that
* grows to a bound of CONFIG_CONSOLE_CAR_BUFFER_SIZE. However,
* collisions within the cache-as-ram region cannot be
* statically checked because the cache-as-ram region usage is
* cpu/chipset dependent. */
*(.car.cbmem_console);
_car_data_end = .;
}
_bogus = ASSERT((SIZEOF(.car.data) <= CONFIG_DCACHE_RAM_SIZE), "Cache as RAM area is too full");