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Re: [Qemu-devel] [PATCH v1 01/40] trace: add build framework for merging
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH v1 01/40] trace: add build framework for merging trace-events files |
Date: |
Wed, 15 Jun 2016 09:39:41 +0100 |
User-agent: |
Mutt/1.6.1 (2016-04-27) |
On Tue, Jun 14, 2016 at 03:53:48PM -0600, Eric Blake wrote:
> On 06/14/2016 06:26 AM, Stefan Hajnoczi wrote:
> > On Thu, Jun 09, 2016 at 05:57:55PM +0100, Daniel P. Berrange wrote:
> >> +$(BUILD_DIR)/trace-events-all: $(trace-events-y:%=$(SRC_PATH)/%)
> >> + $(call quiet-command,cat $^ > $@)
> >
> > $^ needs to be a stable ordering across make invocations and across
> > machines to avoid thrashing ccache and spuriously renumbering trace
> > event IDs.
> >
> > I guess it is stable but just in case anyone knows of a case where $^
> > would change order without any changes to the actual files (e.g.
> > readdir(2) returning things in a different order, make parallel jobs,
> > etc)...
>
> As far as I can tell from 'info make', $^ is the list of prerequisites,
> _in prerequisite order_, minus duplicates. So the only way the order
> will change is if you edit Makefile, and thus it looks stable to me.
Thanks for confirming.
Stefan
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- [Qemu-devel] [PATCH v1 00/40] Split up the trace-events file, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 02/40] trace: split out trace events for util/ directory, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 07/40] trace: split out trace events for hw/block/ directory, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 04/40] trace: split out trace events for io/ directory, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 06/40] trace: split out trace events for block/ directory, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 08/40] trace: split out trace events for hw/char/ directory, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 05/40] trace: split out trace events for migration/ directory, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 11/40] trace: split out trace events for hw/virtio/ directory, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 13/40] trace: split out trace events for hw/misc/ directory, Daniel P. Berrange, 2016/06/09
- [Qemu-devel] [PATCH v1 09/40] trace: split out trace events for hw/intc/ directory, Daniel P. Berrange, 2016/06/09