Re: [RFC PATCH] configure: Poison (almost) all target-specific #defines

[Thomas Huth <thuth@redhat.com>]

On 15/03/2021 15.52, Philippe Mathieu-Daudé wrote:
> On 3/15/21 2:54 PM, Thomas Huth wrote:
>> We are generating a lot of target-specific defines in the *-config-devices.h
>> and *-config-target.h files. Using them in common code is wrong and leads
>> to very subtle bugs since a "#ifdef CONFIG_SOMETHING" is not working there
>> as expected. To avoid these issues, we are already poisoning some of the
>> macros in include/exec/poison.h - but maintaining this list manually is
>> cumbersome. Thus let's generate the list of poisoned macros automatically
>> instead.
>> Note that CONFIG_TCG (which is also defined in config-host.h) and
> 
> IIRC we can't poison CONFIG_XEN / CONFIG_HAX because they are
> pulled in via "sysemu/hw_accel.h".

That's a good hint ... but I think it can be fixed with a patch like this:

diff a/include/sysemu/hw_accel.h b/include/sysemu/hw_accel.h
--- a/include/sysemu/hw_accel.h
+++ b/include/sysemu/hw_accel.h
@@ -12,19 +12,24 @@
  #define QEMU_HW_ACCEL_H

  #include "hw/core/cpu.h"
+
+#ifdef NEED_CPU_H
+
  #include "sysemu/hax.h"
  #include "sysemu/kvm.h"
  #include "sysemu/hvf.h"
  #include "sysemu/whpx.h"

-void cpu_synchronize_state(CPUState *cpu);
-void cpu_synchronize_post_reset(CPUState *cpu);
-void cpu_synchronize_post_init(CPUState *cpu);
-void cpu_synchronize_pre_loadvm(CPUState *cpu);
-
  static inline bool cpu_check_are_resettable(void)
  {
      return kvm_enabled() ? kvm_cpu_check_are_resettable() : true;
  }

+#endif
+
+void cpu_synchronize_state(CPUState *cpu);
+void cpu_synchronize_post_reset(CPUState *cpu);
+void cpu_synchronize_post_init(CPUState *cpu);
+void cpu_synchronize_pre_loadvm(CPUState *cpu);
+
  #endif /* QEMU_HW_ACCEL_H */

  Thomas