Eric Blake <[email protected]> writes: > On 11/10/20 11:47 PM, Ben Widawsky wrote: >> A CXL memory device (AKA Type 3) is a CXL component that contains some >> combination of volatile and persistent memory. It also implements the >> previously defined mailbox interface as well as the memory device >> firmware interface. >> >> The following example will create a 256M device in a 512M window: >> >> -object "memory-backend-file,id=cxl-mem1,share,mem-path=cxl-type3,size=512M" >> -device "cxl-type3,bus=rp0,memdev=cxl-mem1,id=cxl-pmem0,size=256M" >> >> Signed-off-by: Ben Widawsky <[email protected]> >> --- > >> +++ b/qapi/machine.json >> @@ -1394,6 +1394,7 @@ >> { 'union': 'MemoryDeviceInfo', >> 'data': { 'dimm': 'PCDIMMDeviceInfo', >> 'nvdimm': 'PCDIMMDeviceInfo', >> + 'cxl': 'PCDIMMDeviceInfo', >> 'virtio-pmem': 'VirtioPMEMDeviceInfo', >> 'virtio-mem': 'VirtioMEMDeviceInfo' >> } > > Missing documentation of the new data type, and the fact that it will be > introduced in 6.0.
Old wish list item: improve the QAPI schema frontend to flag this. > Also, Markus has been trying to get rid of so-called > "simple unions" in favor of "flat unions" - every time we modify an > existing simple union, it is worth asking if it is time to first flatten > this. 0. Simple unions can be transformed into flat unions. The transformation can either preserve the nested wire format, or flatten it. See docs/devel/qapi-code-gen.txt "A simple union can always be re-written as a flat union ..." 1. No new simple unions. 2. Existing simple unions that can be flattened without breaking backward compatibility have long been flattened. 3. The remaining simple unions are part of QMP, where we need to preserve the wire format. We could turn them into flat union preserving the wire format. Only worthwhile if we kill simple unions and simplify scripts/qapi/. Opportunity to make the flat union syntax less cumbersome. Not done due to lack of time. 4. Kevin and I have been experimenting with ways to provide both flat and nested wire format. This would pave the way for orderly deprecation of the nested wire format. May not be practical for QMP output.
