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Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and
From: |
Anthony Liguori |
Subject: |
Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c |
Date: |
Wed, 01 Aug 2012 15:47:00 -0500 |
User-agent: |
Notmuch/0.13.2+93~ged93d79 (http://notmuchmail.org) Emacs/23.3.1 (x86_64-pc-linux-gnu) |
Andreas Färber <address@hidden> writes:
> Am 01.08.2012 22:02, schrieb Anthony Liguori:
>> Devices do one of two things today:
>>
>> 1) register a reset callback
>>
>> 2) implement a reset method that is invoked through it's parent bus
>>
>> Since I don't expect CPUs to exist on a bus, it's not immediately clear
>> to me that (1) isn't going to be what we do for quite some time.
>
> Err, I thought devices implement a function assigned to a
> DeviceClass::reset, no? That would be (2) on your list and we've been
> working on ripping out (1) for devices, on sPAPR for instance.
> (2) is what we already have with CPUClass::reset.
Something has to call DeviceClass::reset. That's done through a
BusState. Whenever a bus is created, a qemu_register_reset() call is
made to invoke the reset method on any device that's part of the bus.
So just implementing DeviceClass::reset doesn't automatically mean the
reset function will be called. In the short term, I think we'll need to
still register a reset handler.
> The only remaining issue is that the CPUClass::reset callback is not
> automatically called on machine/bus reset yet.
>
> And what I was saying is that moving the code is NOT an improvement. It
> is NO functional change and it is NOT a prerequisite for any change on
> the list today. So it is not needed for the to be released 1.2.
>
> A very low hanging fruit for 1.2 would be to register a SINGLE central
> reset callback that iterates through the globally available CPU list and
> calls ->reset on each! Then we can drop the reset callbacks in most
> machines rather than moving old code around.
Relying on the CPU list for this isn't very QOM-like. A better approach
would be to make all CPUs appear in a container and then have the reset
propagate through container.
Reset is a complicated beast. While we model a single reset line today,
this isn't technically correct. I believe the distinction between reset
types start to matter with PCI-e actually.
I do think any reduction in what's happening in machine is a net win.
Even if we refactor this later, having the machine code do less and
devices do more is an improvement.
Regards,
Anthony Liguori
>
> Regards,
> Andreas
>
>>
>> Regards,
>>
>> Anthony Liguori
>>
>>>
>>> Regards,
>>> Andreas
>>>
>>> --
>>> SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
>>> GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
>>
>
>
> --
> SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg, Germany
> GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer; HRB 16746 AG Nürnberg
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Anthony Liguori, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Andreas Färber, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Anthony Liguori, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Andreas Färber, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Anthony Liguori, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Andreas Färber, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c,
Anthony Liguori <=
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Andreas Färber, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Peter Maydell, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Andreas Färber, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Igor Mammedov, 2012/08/02
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Andreas Färber, 2012/08/01
- Re: [Qemu-devel] [PATCH 0/2 v3] target-i386: refactor reset handling and move it into cpu.c, Anthony Liguori, 2012/08/01