In rom_check_and_register_reset() we detect overlaps by looking at
whether the ROM blob we're currently examining is in the same address
space and starts before the previous ROM blob ends.  (This works
because the ROM list is kept sorted in order by AddressSpace and then
by address.)

Instead of keeping the AddressSpace and last address of the previous ROM
blob in local variables, just keep a pointer to it.

This will allow us to print more useful information when we do detect
an overlap.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 hw/core/loader.c | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/hw/core/loader.c b/hw/core/loader.c
index 8bbb1797a4c..05052ee797e 100644
--- a/hw/core/loader.c
+++ b/hw/core/loader.c
@@ -1165,28 +1165,35 @@ static void rom_reset(void *unused)
     }
 }
 
+/* Return true if two consecutive ROMs in the ROM list overlap */
+static bool roms_overlap(Rom *last_rom, Rom *this_rom)
+{
+    if (!last_rom) {
+        return false;
+    }
+    return last_rom->as == this_rom->as &&
+        last_rom->addr + last_rom->romsize > this_rom->addr;
+}
+
 int rom_check_and_register_reset(void)
 {
-    hwaddr addr = 0;
     MemoryRegionSection section;
-    Rom *rom;
-    AddressSpace *as = NULL;
+    Rom *rom, *last_rom = NULL;
 
     QTAILQ_FOREACH(rom, &roms, next) {
         if (rom->fw_file) {
             continue;
         }
         if (!rom->mr) {
-            if ((addr > rom->addr) && (as == rom->as)) {
+            if (roms_overlap(last_rom, rom)) {
                 fprintf(stderr, "rom: requested regions overlap "
                         "(rom %s. free=0x" TARGET_FMT_plx
                         ", addr=0x" TARGET_FMT_plx ")\n",
-                        rom->name, addr, rom->addr);
+                        rom->name, last_rom->addr + last_rom->romsize,
+                        rom->addr);
                 return -1;
             }
-            addr  = rom->addr;
-            addr += rom->romsize;
-            as = rom->as;
+            last_rom = rom;
         }
         section = memory_region_find(rom->mr ? rom->mr : get_system_memory(),
                                      rom->addr, 1);
-- 
2.20.1

On 11/29/20 2:39 PM, Peter Maydell wrote:
> In rom_check_and_register_reset() we detect overlaps by looking at
> whether the ROM blob we're currently examining is in the same address
> space and starts before the previous ROM blob ends.  (This works
> because the ROM list is kept sorted in order by AddressSpace and then
> by address.)
> 
> Instead of keeping the AddressSpace and last address of the previous ROM
> blob in local variables, just keep a pointer to it.
> 
> This will allow us to print more useful information when we do detect
> an overlap.
> 
> Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
> ---
>  hw/core/loader.c | 23 +++++++++++++++--------
>  1 file changed, 15 insertions(+), 8 deletions(-)

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

r~