Re: [PATCH 0/3] eliminate remaining places that abuse memory_region_allocate_system_memory()

[Philippe Mathieu-Daudé]

Hi Igor,

On 10/8/19 1:33 PM, Igor Mammedov wrote:
> Series cleans up remaining boards that call 
> memory_region_allocate_system_memory()
> multiple times, violating interface contract (the function should be called only
> once).
>
> With that cleaned up, it should be possible to switch from adhoc RAM allocation
> in memory_region_allocate_system_memory()->allocate_system_memory_nonnuma() to
> memory-backend based allocation, remaining roadblock for doing it is deprecated
> -mem-path fallback to RAM allocation, which is scheduled for removal at 4.3
> merge window. So remaining patches to consolidate system RAM allocation around
> memory-backends and aliasing -mem-path/mem-prealloc to it are postponed till
> then.

How do we protect the codebase for new boards to not make the same mistake?

What about some code like this snippet (or nicer, but since this is a 
developer error, and assert is enough IMO):

-- >8 --

diff --git a/hw/core/numa.c b/hw/core/numa.c
index 4dfec5c95b..a487677672 100644
--- a/hw/core/numa.c
+++ b/hw/core/numa.c
@@ -484,6 +484,11 @@ static void 
allocate_system_memory_nonnuma(MemoryRegion *mr, Object *owner,
                                            const char *name,
                                            uint64_t ram_size)
 {
+    static bool nonnuma_system_memory_allocated;
+
+    g_assert(!nonnuma_system_memory_allocated);
+    nonnuma_system_memory_allocated = true;
+
     if (mem_path) {
 #ifdef __linux__
         Error *err = NULL;
---

$ hppa-softmmu/qemu-system-hppa
**
ERROR:/home/phil/source/qemu/hw/core/numa.c:489:allocate_system_memory_nonnuma: 
assertion failed: (!nonnuma_system_memory_allocated)
Aborted (core dumped)