> Am 30.06.2014 um 23:47 schrieb "Stalley, Sean" <sean.stal...@intel.com>: > > > >> -----Original Message----- >> From: Alexander Graf [mailto:ag...@suse.de] >> Sent: Monday, June 30, 2014 1:22 PM >> To: Stalley, Sean; Peter Crosthwaite >> Cc: qemu-devel@nongnu.org >> Subject: Re: [Qemu-devel] Adding memory region without specifying address >> >> >>> On 30.06.14 19:53, Stalley, Sean wrote: >>> Thanks for the quick response! Sorry for my belated reply... >>> >>>> -----Original Message----- >>>> From: peter.crosthwa...@petalogix.com >>>> [mailto:peter.crosthwa...@petalogix.com] On Behalf Of Peter >>>> Crosthwaite >>>> Sent: Friday, June 27, 2014 6:26 PM >>>> To: Stalley, Sean; Alexander Graf >>>> Cc: qemu-devel@nongnu.org >>>> Subject: Re: [Qemu-devel] Adding memory region without specifying >>>> address >>>> >>>> On Sat, Jun 28, 2014 at 10:29 AM, Stalley, Sean <sean.stal...@intel.com> >> wrote: >>>>> Hello All, >>>>> >>>>> >>>>> >>>>> I am working on building a hardware model for QEMU. This model needs >>>>> a couple memory regions for MMIO. >>>>> >>>>> The thing is, I don’t particularly care what the physical address of >>>>> the memory region is (so long as it doesn’t overlap with any other >>>>> memory region). >>>> Curious, what's your mechanism for giving the auto allocated address >>>> to the guest? >>> We have one memory space that is fixed. The plan is to put the addresses of >> the automatically allocated locations in the fixed space. >> >> That sounds exactly like what I've been working on. The first incarnation was >> called "platform bus", the second "platform devices", the current work is >> going >> to be "sysbus hints" - but it's WIP. > > Hmm, it sounds very similar. Out of curiosity, is there any relation to Linux > platform devices?
There's inspiration from them. After all, both are basically abstractions of the same things ;). > >> >>> >>>>> >>>>> I was wondering if QEMU is able to ‘allocate’ a memory region for >>>>> hardware >>>>> (IE: I call into something saying I need a memory region X bytes long, >>>>> and QEMU returns with a pointer to a memory region X bytes long). >>>> Do you have full control over the memory region you are adding these sub- >>>> regions too and can you implement a "for-everything" allocator on the >> machine >>>> level? >>> We want to be able to put these sub-regions anywhere in memory-space, so a >> "for-everything" allocator isn't really a good option. >> >> Why not? > > I think I misinterpreted the meaning of the term 'full control'. > Right now, the sole purpose of the guest machine is to validate this hardware > model. I can change the hardware models in the guest as needed (although I > hope to keep them the same). In that sense, I have full control over the > memory region. > >> >>> >>>>> >>>>> Can QEMU do this? was looking at the various flavors of >>>>> memory_region_add_subregion(), but they all seem to require a hardware >>>>> offset… >>>> Alex's addressless -device work may be related but it's more about command >>>> line usability. Autoallocation of MMIO addresses is a feature there >>>> however. >>> Where is this code located? I have been looking, but I haven’t been able to >>> find >> it yet. Is this called by qdev_device_add()? >> >> It's not upstream yet ;). > > Aah, that explains why I couldn't find it :P > > > It seems like the answer to my initial question, "can qemu add a memory > region for hardware without being given a specific address" is "Not yet". Exactly. But you can also add a "it will very soon". :) Alex > > Thanks, > Sean
