Re: [PATCH-for-5.2] memory: Display bigger regions first in 'info mtree' output

[Peter Maydell]

On Mon, 27 Jul 2020 at 18:46, Philippe Mathieu-Daudé <f4bug@amsat.org> wrote:
>
> When different regions have the same address, we currently
> sort them by the priority. Also sort them by the region
> size.
>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
> ---
>  softmmu/memory.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/softmmu/memory.c b/softmmu/memory.c
> index af25987518..c28dcaf4d6 100644
> --- a/softmmu/memory.c
> +++ b/softmmu/memory.c
> @@ -2960,7 +2960,8 @@ static void mtree_print_mr(const MemoryRegion *mr, 
> unsigned int level,
>          QTAILQ_FOREACH(ml, &submr_print_queue, mrqueue) {
>              if (new_ml->mr->addr < ml->mr->addr ||
>                  (new_ml->mr->addr == ml->mr->addr &&
> -                 new_ml->mr->priority > ml->mr->priority)) {
> +                 (MR_SIZE(new_ml->mr->size) > MR_SIZE(ml->mr->size) ||
> +                  new_ml->mr->priority > ml->mr->priority))) {
>                  QTAILQ_INSERT_BEFORE(ml, new_ml, mrqueue);
>                  new_ml = NULL;
>                  break;

I think this is the point where you want to factor out the
comparison-of-two-MRs function. Which then makes it easier
to implement the required logic, which as Peter Xu says
should be "address compare first; if those are equal look
at the priority; if those are also equal look at the size",
ie the usual comparison-with-multiple-fields.

thanks
-- PMM