core: Allow .bss and .data sections in DRAM

We manually copy other .data from the original section on boot, and
clear DRAM .bss.

This way, a single object file (or archive) can be moved fully to
DRAM.

BRANCH=none
BUG=b:122058243
TEST=With next CL, dram_test works

Change-Id: I1a434bbd8a4135d16b3f49b0d1b75b96506e3e24
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/1445652
Reviewed-by: Jett Rink <jettrink@chromium.org>

1 files changed, 27 insertions, 0 deletions

diff --git a/core/cortex-m/ec.lds.S b/core/cortex-m/ec.lds.S
index 06bd83a30d..28c3e691cd 100644
--- a/core/cortex-m/ec.lds.S
+++ b/core/cortex-m/ec.lds.S
@@ -444,7 +444,34 @@ SECTIONS
 #endif /* CONFIG_CHIP_MEMORY_REGIONS */
 
 #ifdef CONFIG_DRAM_BASE
+    /* Allocate space for original copy of .data.dram (see .data_lma above). */
+    .dram.data_lma : {
+        __dram_data_lma_start = .;
+        . += __dram_data_end - __dram_data_start;
+    } > DRAM
+
+    /*
+     * TODO(b:122058243): Both .dram.data and .dram.bss do not actually
+     * need to be in the final image, as we have a second copy of the data
+     * (just above), and dram.bss is zeroed anyway.
+     */
+    .dram.data : AT(ADDR(.dram.data_lma)) {
+        . = ALIGN(4);
+        __dram_data_start = .;
+        *(.dram.data*)
+        __dram_data_end = .;
+    } > DRAM
+
+    .dram.bss : {
+        . = ALIGN(4);
+        __dram_bss_start = .;
+        *(SORT(.dram.bss*))
+        __dram_bss_end = .;
+    } > DRAM
+
+    /* Rest of DRAM sections, e.g. text. */
     .dram : {
+        . = ALIGN(4);
         KEEP(*(SORT(.dram.keep.*)))
         *(SORT(.dram.*))
     } > DRAM