[Qemu-devel] [PATCH 1/2] memory: Align and add helper for comparing MemoryRegionSections

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

MemoryRegionSection includes an Int128 'size' field;
on some platforms the compiler causes an alignment of this to
a 128bit boundary, leaving 8 bytes of dead space.
This deadspace can be filled with junk.

Move the size field to the top avoiding unnecsssary alignment
and provide an 'eq' routine to safely compare MRS's.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 include/exec/memory.h | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/include/exec/memory.h b/include/exec/memory.h
index 606250172a..ce62e847bd 100644
--- a/include/exec/memory.h
+++ b/include/exec/memory.h
@@ -487,15 +487,27 @@ static inline FlatView *address_space_to_flatview(AddressSpace *as)
  * @nonvolatile: this section is non-volatile
  */
 struct MemoryRegionSection {
+    Int128 size;
     MemoryRegion *mr;
     FlatView *fv;
     hwaddr offset_within_region;
-    Int128 size;
     hwaddr offset_within_address_space;
     bool readonly;
     bool nonvolatile;
 };
 
+static inline bool MemoryRegionSection_eq(MemoryRegionSection *a,
+                                          MemoryRegionSection *b)
+{
+    return a->mr == b->mr &&
+           a->fv == b->fv &&
+           a->offset_within_region == b->offset_within_region &&
+           a->offset_within_address_space == b->offset_within_address_space &&
+           int128_eq(a->size, b->size) &&
+           a->readonly == b->readonly &&
+           a->nonvolatile == b->nonvolatile;
+}
+
 /**
  * memory_region_init: Initialize a memory region
  *
-- 
2.21.0