Changeset 552 for trunk/boot

Timestamp:

Sep 21, 2018, 10:24:44 PM (6 years ago)

Author:

nicolas.van.phan@…

Message:

Stop fetching instructions from local cluster

At the beginning of the bootloader, all cores in all clusters fetch
their instruction from the memory bank of *cluster 00*.
After replication of the code in all cluster, the cores would
fetch their instruction in their own cluster.
However, to do this, they have to write to coprocessor 2 register 25,
which doesn't exist on the real LETI machine.
As a consequence, this feature has been removed, bringing a contention
point since all cluster now fetch instructions from cluster 00.
This issue will have to be solved in the future.

File:

• trunk/boot/tsar_mips32/boot.c (modified) (2 diffs)

trunk/boot/tsar_mips32/boot.c

@@ -865 +865 @@
 
                         // switch to the INSTRUCTION local memory space, to avoid contention.
-            asm volatile("mtc2  %0, $25" :: "r"(cxy));
+            // asm volatile("mtc2  %0, $25" :: "r"(cxy));
 
             // Copy the arch_info.bin file into the local memory.
@@ -932 +932 @@
         // Switch to the INSTRUCTIONS local memory space 
         // to avoid contention at the boot cluster.
-        asm volatile("mtc2  %0, $25" :: "r"(cxy));
+        // asm volatile("mtc2  %0, $25" :: "r"(cxy));
 
         // Get local boot_info_t structure base address.