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| author | Aseda Aboagye <aaboagye@google.com> | 2015-11-04 13:40:49 -0800 |
|---|---|---|
| committer | chrome-bot <chrome-bot@chromium.org> | 2015-11-08 07:59:40 -0800 |
| commit | da87d12ec838d3d54d80c7ff3c92b8cc81cf59f6 (patch) | |
| tree | 5f03c581efda57f7b8b257ae9eb5edf54251709a /include | |
| parent | 260e85cd07135c4d7ab2696ac1cc8212e092ecdb (diff) | |
| download | chrome-ec-da87d12ec838d3d54d80c7ff3c92b8cc81cf59f6.tar.gz | |
common.h: Create __bss_slow tag.
Some ECs such as the MEC1322 have a data RAM optimized region as well as
a code RAM optimized region. We discovered that we could save quite a
bit more space by reusing the a portion of the code RAM region as an
additional .bss section. However, this region resides in the code RAM
region. If on the same cycle the processor fetches an instruction and
does a load or store to this code RAM region, the data access will be
delayed by one cycle. Hence, the naming of ``.bss.slow" section.
For boards which do not define CONFIG_REUSE_LOADER_WITH_BSS_SLOW, all
objects bearing this tag will be simply appended to the existing .bss
section.
BUG=chrome-os-partner:46056
BUG=chrome-os-partner:46063
BRANCH=None
TEST=make -j buildall tests
CQ-DEPEND=CL:306173
Change-Id: I126fbeee5255732a6dd6fea1d4557fc2b2c62c96
Signed-off-by: Aseda Aboagye <aaboagye@google.com>
Reviewed-on: https://chromium-review.googlesource.com/311209
Commit-Ready: Aseda Aboagye <aaboagye@chromium.org>
Tested-by: Aseda Aboagye <aaboagye@chromium.org>
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/common.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/common.h b/include/common.h index fe51a9b79b..84b9366064 100644 --- a/include/common.h +++ b/include/common.h @@ -68,6 +68,16 @@ #define __keep __attribute__((used)) __attribute__((externally_visible)) #endif +/* + * Place the object in the .bss.slow region. + * + * On boards with unoptimized RAM there is no penalty and it simply is appended + * to the .bss section. + */ +#ifndef __bss_slow +#define __bss_slow __attribute__((section(".bss.slow"))) +#endif + /* There isn't really a better place for this */ #define C_TO_K(temp_c) ((temp_c) + 273) #define K_TO_C(temp_c) ((temp_c) - 273) |