On Fri, 8 Sept 2023 at 15:37, Kevin Wolf <kw...@redhat.com> wrote: > > Until now, array properties are actually implemented with a hack that > uses multiple properties on the QOM level: a static "foo-len" property > and after it is set, dynamically created "foo[i]" properties. > > In external interfaces (-device on the command line and device_add in > QMP), this interface was broken by commit f3558b1b ('qdev: Base object > creation on QDict rather than QemuOpts') because QDicts are unordered > and therefore it could happen that QEMU tried to set the indexed > properties before setting the length, which fails and effectively makes > array properties inaccessible. In particular, this affects the 'ports' > property of the 'rocker' device. > > This patch reworks the external interface so that instead of using a > separate top-level property for the length and for each element, we use > a single true array property that accepts a list value. In the external > interfaces, this is naturally expressed as a JSON list and makes array > properties accessible again. > > Creating an array property on the command line without using JSON format > is currently not possible. This could be fixed by switching from > QemuOpts to a keyval parser, which however requires consideration of the > compatibility implications.
Could we have a specific example in the commit message of: The old (currently broken) syntax for setting the ports property on the rocker device is: -device rocker,len-ports=2,ports[0]=dev0,ports[1]=dev1 The new syntax that works as of this commit is: [whatever] ? I would expect most users have no idea what the JSON list syntax is. thanks -- PMM