Re: [Qemu-devel] [RFC] Memory API and fine grained Memory Regions

2012-10-30 Thread Edgar E. Iglesias
On Mon, Oct 29, 2012 at 06:34:37PM +0200, Avi Kivity wrote: > On 10/29/2012 01:37 AM, John Williams wrote: > > >> IMO, an mr per reg would just add a massive overhead for no win. > > > > I tend to agree with Edgar here - QEMU has a careful line to walk between > > being an emulator and an RTL si

Re: [Qemu-devel] [RFC] Memory API and fine grained Memory Regions

2012-10-29 Thread Avi Kivity
On 10/29/2012 01:37 AM, John Williams wrote: >> IMO, an mr per reg would just add a massive overhead for no win. > > I tend to agree with Edgar here - QEMU has a careful line to walk between > being an emulator and an RTL simulator. > > Any WAG on the runtime overhead of a mem region per regist

Re: [Qemu-devel] [RFC] Memory API and fine grained Memory Regions

2012-10-29 Thread Avi Kivity
On 10/27/2012 06:12 AM, Edgar E. Iglesias wrote: > > Hi, > > If well designed, most hw has a well designed symtery between regs > that makes things simpler if you can just opencode the decding. > IMO, an mr per reg would just add a massive overhead for no win. > And also, hw implemented decoders

Re: [Qemu-devel] [RFC] Memory API and fine grained Memory Regions

2012-10-28 Thread John Williams
> -Original Message- > From: Edgar E. Iglesias [mailto:edgar.igles...@gmail.com] > Sent: Saturday, 27 October 2012 2:12 PM > To: Peter Crosthwaite > Cc: qemu-devel@nongnu.org Developers; Avi Kivity; Peter Maydell; John > Williams > Subject: Re: [Qemu-devel] [RFC

Re: [Qemu-devel] [RFC] Memory API and fine grained Memory Regions

2012-10-26 Thread Edgar E. Iglesias
On Fri, Oct 26, 2012 at 05:03:04PM +1000, Peter Crosthwaite wrote: > In my recent USB series Avi mentioned he wanted to do some work with > the memory API and encourage devices to use the memory API to do > fine-grained register decoding, i.e. each register is its own > MemoryRegion. This has the a

Re: [Qemu-devel] [RFC] Memory API and fine grained Memory Regions

2012-10-26 Thread Gerd Hoffmann
Hi, > For actually writing into the device registers, its just uses an array > index, no need to switch (ret = s->regs[addr]). However for my side > effects I will need to populate that switch. If we convert to fine > grained memory regions then the switch goes away and my side effect > become p