Hello Daniel, On Tue, Sep 24, 2024, 3:08 PM Daniel P. Berrangé <berra...@redhat.com> wrote:
> On Tue, Sep 24, 2024 at 01:02:26PM +0100, Alex Bennée wrote: > > Manos Pitsidianakis <manos.pitsidiana...@linaro.org> writes: > > > > > Hello Daniel, > > > > > > On Tue, 24 Sept 2024 at 11:45, Daniel P. Berrangé <berra...@redhat.com> > wrote: > > >> > > >> On Mon, Sep 23, 2024 at 10:09:32PM +0300, Manos Pitsidianakis wrote: > > >> > Hello Daniel, > > >> > > > >> > On Mon, 23 Sep 2024 19:45, "Daniel P. Berrangé" < > berra...@redhat.com> wrote: > > >> > > On Mon, Sep 23, 2024 at 09:05:24AM +0300, Manos Pitsidianakis > wrote: > > <snip> > > >> > > ie, look a query-audiodevs to discover what audio baxckends are > > >> > > built-in, don't look for CONFIG_XXX settings related to audio. > > >> > > If there are gaps in information we can query from QMP, we should > > >> > > aim to close those gaps. > > >> > > > > >> > > IOW, I don't think we should expose this build info info in either > > >> > > human readable or machine readable format. > > >> > > > >> > QAPI/QMP is not the perspective of this patch, this is for people > who use > > >> > custom-built (i.e. not from a distro) binaries and want to be able > to > > >> > identify how it was built. Launching a binary to query stuff is > > >> > unnecessarily complex for this task, and the info is not generally > > >> > interesting to the API consumers as you said. > > >> > > >> Launching QEMU to talk QMP is our defined public API for querying > > >> anything about the capabilities of QEMU. We're worked hard to get > > >> away from providing ad-hoc ways to query QEMU from the command > > >> line and going back to that is not desirable. It may be slightly > > >> more complicated, but not by very much. > > > > > > Again, this is not a "capabilities discovery" API. It lists the > > > build-time configuration of the binary. Perhaps we can expose it in a > > > different way so that people don't end up confused? > > > > I think the problem is however much we might say it's not a capabilities > > discovery API it's very existence encourages users to use it as one. > > > > What about a script: > > > > qemu-get-build-info </path/to/qemu> > > > > which would launch the binary and query it over QMP? Would that work? > > If this is purely a debugging aid, we could make use of ELF notes to > just stick the config-host.h content into the binary. This has precedent > in systemd package notes (https://github.com/systemd/package-notes) and > is more clearly *NOT* an end user CLI option, nor a public API in QMP. > > Querying is then > > objdump -j .note.qemu-config-h -s /usrbin/qemu-system-x86_64 > That's actually a way better solution! I will attempt it for the next revision. Manos >
