On Fri, May 3, 2013 at 4:04 PM, Jan Kiszka <jan.kis...@siemens.com> wrote: > On 2013-05-03 09:37, liu ping fan wrote: >> On Fri, May 3, 2013 at 12:58 AM, Jan Kiszka <jan.kis...@siemens.com> wrote: >>> Hi Pingfan, >>> >>> On 2012-12-06 08:28, liu ping fan wrote: >>>> Any suggestion? Or new design idea for this? >>> >>> Finally... I'm getting back to this. I'm currently trying to make use of >>> this series, adapting it to my needs (selective BQL-free dispatching of >>> PIO regions). >>> >> Glad that you are back :) >> >>> Is there a newer version available on your side? This one obviously no >> >> No, but I can see the code and rebase next week. > > I've already rebased and started to fix/cleanup. Today I will look into > the ref/unref vs. Object topic and try a first unlocked device model. I > can share afterward so that we do not need to do the work twice. > Ok, thanks. >> >>> longer applies due to all the code movements in QEMU. But it also seems >>> to contain some bugs, at least in patch 5 (mixed up page number vs. page >>> address around for address_space_section_lookup_ref). >>> >> Will pay some time to see it. > > Fixed. Specifically subpages were broken. As I've converted portio to > use the memory core dispatcher, I'm getting a lot of them now and > triggered the bugs immediately. > > There is still some nesting issue around coalesced MMIO flushing. Need > to look into this today as well. So far I've worked around it by > assuming that nesting is fine if we enter the dispatcher with BQL held. > >> >>> Then we should get rid of the ref/unref callbacks. Making a memory >>> region BQL-free must be as simple as setting a flag or (more likely) >>> adding a reference to the owning QOM object in the region. >>> Reimplementing ref/unref in device models over and over again is clearly >>> a no-go. Maybe I'm currently forgetting a use case where overloading the >> >> At the beginning, Avi suggest to enforce mr->opaque to be Device >> object, but due to the nested embedded Object, we fail. And finally >> Avi suggest ref/unref interface. >> From my point, we can save lots of reimplementing ref/unref in device >> models by telling whether mr->opauque is Object or not. And leave not >> object case to reimplement ref/unref. > > We can't change the semantics of opaque as long as old_mmio / old_portio > are around. But we need a flag anyway to indicate if a region is > depending on BQL or not. Adding a separate "Object *owner" to > MemoryRegion can serve both purposes. Then we define something like > > void memory_region_set_local_locking(MemoryRegion *mr, > bool local_locking, > Object *owner); > I think, owner imply local_locking, so we need not call this function for each device, just those we plan to push out of biglock
> to control the property (if local_locking is true, owner must be > non-NULL, of course). That's quite similar to my old prototype here that > had memory_region_set/clear_global_locking. > > Jan > > -- > Siemens AG, Corporate Technology, CT RTC ITP SDP-DE > Corporate Competence Center Embedded Linux
