Reserve a portion of DCCM for future changes to PersistentData.

* Reserved 44K. * Left 32K for BSS. Current BSS size is 16K. This resolves chipsalliance#1662.
clundin25 · Oct 28, 2024 · 8a54c60 · 8a54c60
1 parent f102017
commit 8a54c60
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Showing 2 changed files with 14 additions and 4 deletions.
diff --git a/drivers/src/memory_layout.rs b/drivers/src/memory_layout.rs
@@ -40,7 +40,8 @@ pub const FUSE_LOG_ORG: u32 = 0x50005000;
 pub const DPE_ORG: u32 = 0x50005400;
 pub const PCR_RESET_COUNTER_ORG: u32 = 0x50006800;
 pub const AUTH_MAN_IMAGE_METADATA_LIST_ORG: u32 = 0x50006C00;
-pub const DATA_ORG: u32 = 0x50007000;
+pub const RESERVED_MEMORY_ORG: u32 = 0x50007000;
+pub const DATA_ORG: u32 = 0x50011000;
 
 pub const STACK_ORG: u32 = 0x5001A000;
 pub const ROM_STACK_ORG: u32 = 0x5001C000;
@@ -72,7 +73,8 @@ pub const FUSE_LOG_SIZE: u32 = 1024;
 pub const DPE_SIZE: u32 = 5 * 1024;
 pub const PCR_RESET_COUNTER_SIZE: u32 = 1024;
 pub const AUTH_MAN_IMAGE_METADATA_LIST_MAX_SIZE: u32 = 1024;
-pub const DATA_SIZE: u32 = 76 * 1024;
+pub const RESERVED_MEMORY_SIZE: u32 = 40 * 1024;
+pub const DATA_SIZE: u32 = 36 * 1024;
 pub const STACK_SIZE: u32 = 22 * 1024;
 pub const ROM_STACK_SIZE: u32 = 14 * 1024;
 pub const ESTACK_SIZE: u32 = 1024;

diff --git a/drivers/src/persistent.rs b/drivers/src/persistent.rs
@@ -101,6 +101,11 @@ pub struct PersistentData {
     #[cfg(not(feature = "runtime"))]
     pub auth_manifest_image_metadata_col:
         [u8; memory_layout::AUTH_MAN_IMAGE_METADATA_LIST_MAX_SIZE as usize],
+
+    // Reserved memory for future objects.
+    // New objects should always source memory from this range.
+    // Taking memory from this reserve does NOT break hitless updates.
+    pub reserved_memory: [u8; memory_layout::RESERVED_MEMORY_SIZE as usize],
 }
 impl PersistentData {
     pub fn assert_matches_layout() {
@@ -128,10 +133,13 @@ impl PersistentData {
                 addr_of!((*P).auth_manifest_image_metadata_col) as u32,
                 memory_layout::AUTH_MAN_IMAGE_METADATA_LIST_ORG
             );
+            assert_eq!(
+                addr_of!((*P).reserved_memory) as u32,
+                memory_layout::RESERVED_MEMORY_ORG
+            );
             assert_eq!(
                 P.add(1) as u32,
-                memory_layout::AUTH_MAN_IMAGE_METADATA_LIST_ORG
-                    + memory_layout::AUTH_MAN_IMAGE_METADATA_LIST_MAX_SIZE
+                memory_layout::RESERVED_MEMORY_ORG + memory_layout::RESERVED_MEMORY_SIZE
             );
         }
     }