If an user creates a RAM region smaller than TARGET_PAGE_SIZE,
this region will be handled as a subpage.
While the subpage behavior can be noticed by an experienced QEMU
developper, it might takes hours to a novice to figure it out.
To save time to novices, do not allow subpage creation via the
memory_region_init_ram_*() functions.
Signed-off-by: Philippe Mathieu-Daudé <f4...@amsat.org>
---
memory.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/memory.c b/memory.c
index e70b64b8b9..51d27b7b26 100644
--- a/memory.c
+++ b/memory.c
@@ -1519,6 +1519,15 @@ void
memory_region_init_ram_shared_nomigrate(MemoryRegion *mr,
bool share,
Error **errp)
{
+ if (size < TARGET_PAGE_SIZE) {
+ /* Region less than PAGE_SIZE are handled as subpages, which are
+ * surely not what the caller expects.
+ * Limit the minimum ram region size to avoid annoying debugging.
+ */
+ error_setg(errp, "Invalid RAM size: %ld (minimum required: %d)",
+ size, TARGET_PAGE_SIZE);
+ return;
+ }
memory_region_init(mr, owner, name, size);
mr->ram = true;
mr->terminates = true;
--
2.16.3
