[prev in list] [next in list] [prev in thread] [next in thread]
List: qemu-block
Subject: Re: [Qemu-block] qom and debug (was: [PATCH for 2.8 02/11] virtio: convert to use DMA api)
From: "Michael S. Tsirkin" <mst () redhat ! com>
Date: 2016-08-30 11:15:14
Message-ID: 20160830141341-mutt-send-email-mst () kernel ! org
[Download RAW message or body]
On Tue, Aug 30, 2016 at 01:11:05PM +0200, Cornelia Huck wrote:
> On Tue, 30 Aug 2016 13:21:23 +0300
> "Michael S. Tsirkin" <mst@redhat.com> wrote:
>
> > BTW downstreams are building with --disable-qom-cast-debug which drops
> > all QOM casts on data path - one way is to say we just make this the
> > default upstream as well. Another to say that we want to distinguish
> > fast path calls from slow path, this way we will be able to bring back
> > some of the checks.
>
> I find CONFIG_QOM_CAST_DEBUG a bit inconsistent, btw:
>
> - for object casts, we optimize away all checks and just return the
> object for !debug
> - for class casts, we optimize away only the caching and still keep the
> checking (why would we drop the caching if this can speed up things?)
>
> We certainly want to have debug turned on during development to avoid
> nasty surprises later (otherwise, why even bother?), but it makes sense
> to turn it off for a release. (Is there an easy way to turn it off for
> the release, normal or stable, and keep it during the development
> cycle?)
I think the assumption was class casts are not on data path.
Ideally we'd keep it on for release too for non-datapath things,
to help improve security.
--
MST
[prev in list] [next in list] [prev in thread] [next in thread]
Configure |
About |
News |
Add a list |
Sponsored by KoreLogic