On 7/3/25 20:28, Pierrick Bouvier wrote:
On 3/7/25 08:49, Philippe Mathieu-Daudé wrote:
On 7/3/25 17:38, Alex Bennée wrote:
Philippe Mathieu-Daudé <phi...@linaro.org> writes:
Use qemu_arch_available() to check at runtime if a target
architecture is built in.
Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
hw/virtio/virtio-mem.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/hw/virtio/virtio-mem.c b/hw/virtio/virtio-mem.c
index 5f57eccbb66..8c40042108c 100644
--- a/hw/virtio/virtio-mem.c
+++ b/hw/virtio/virtio-mem.c
@@ -15,6 +15,7 @@
#include "qemu/cutils.h"
#include "qemu/error-report.h"
#include "qemu/units.h"
+#include "system/arch_init.h"
#include "system/numa.h"
#include "system/system.h"
#include "system/reset.h"
@@ -170,13 +171,16 @@ static bool
virtio_mem_has_shared_zeropage(RAMBlock *rb)
* necessary (as the section size can change). But it's more
likely that the
* section size will rather get smaller and not bigger over time.
*/
-#if defined(TARGET_X86_64) || defined(TARGET_I386) ||
defined(TARGET_S390X)
-#define VIRTIO_MEM_USABLE_EXTENT (2 * (128 * MiB))
-#elif defined(TARGET_ARM)
-#define VIRTIO_MEM_USABLE_EXTENT (2 * (512 * MiB))
-#else
-#error VIRTIO_MEM_USABLE_EXTENT not defined
-#endif
+static uint64_t virtio_mem_usable_extent_size(void)
+{
+ if (qemu_arch_available(QEMU_ARCH_I386 | QEMU_ARCH_S390X)) {
+ return 2 * 128 * MiB;
+ } else if (qemu_arch_available(QEMU_ARCH_ARM)) {
+ return 2 * 512 * MiB;
+ } else {
+ g_assert_not_reached();
+ }
+}
What happens if/when we have multiple arches available? Won't we want to
know which CPU the virtio-mem device is attached to or do we take the
minimal value over the whole system?
"per attached vcpu" is how I was previously considering this problem,
but IIUC from the discussions with Pierrick, we should consider single
binary as a first step before heterogeneous emulation.
I think it's safe to assume only a single arch is enable for now, in the
context of the single binary.
A thing we could do is introduce qemu_arch_heterogenenous_emulation(),
that returns false for now. And assert this in places that will need to
be changed. So spots that will need refactoring will already be flagged
in the codebase.
Yes, after some discussion with Markus I started a branch adding such
macro. I didn't posted it so far waiting to show more realistic changes
w.r.t. heterogeneous emulation, to not add code that could bitrot.
Since we might be at a pivot position, I'll consider rebase and post it.
Reviewed-by: Pierrick Bouvier <pierrick.bouv...@linaro.org>
Thanks!
