[Qemu-devel] Re: [PATCH 4/4] require #define NEED_GLOBAL_ENV for files that need the global register variable

[Blue Swirl <blauwirbel@gmail.com>]

On Fri, Jul 2, 2010 at 9:50 AM, Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 07/01/2010 09:42 PM, Blue Swirl wrote:
>>
>> I still maintain that 'env' may not be unpoisoned until the name is
>> less likely to invite accidents.
>
> The *global* env is still unavailable (i.e. no difference WRT poisoning), by
> virtue of being defined in exec.h which is not available unless -DNEED_CPU_H
> is defined.
>
> So:
>
>            | before                          | after
> ------------+---------------------------------+--------------------------
> NEED_CPU_H  | env not poisoned, global env    | same
>            | available iff exec.h included   |
> ------------+---------------------------------+--------------------------
> !NEED_CPU_H | env poisoned; CPUState          | env not poisoned;
>            | not available, so exec.h cannot | exec.h requires cpu.h
>            | be included                     | so it cannot be included

But why would it be necessary to unpoison 'env' for the lower right
case? Poisoning protects against accidents (in addition to exec.h
thing) and there are no downsides.