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Re: [Qemu-devel] [PULL 17/28] hw/ptimer: Perform counter wrap around if
From: |
Peter Maydell |
Subject: |
Re: [Qemu-devel] [PULL 17/28] hw/ptimer: Perform counter wrap around if timer already expired |
Date: |
Fri, 24 Jun 2016 17:02:38 +0100 |
On 24 June 2016 at 16:58, Mark Cave-Ayland
<address@hidden> wrote:
> On 06/06/16 15:47, Peter Maydell wrote:
>
>> From: Dmitry Osipenko <address@hidden>
>>
>> ptimer_get_count() might be called while QEMU timer already been expired.
>> In that case ptimer would return counter = 0, which might be undesirable
>> in case of polled timer. Do counter wrap around for periodic timer to keep
>> it distributed. In order to achieve more accurate emulation behaviour of
>> certain hardware, don't perform wrap around when in icount mode and return
>> counter = 0 in that case (that doesn't affect polled counter
>> distribution).
>>
> Whilst testing Artyom's qemu-system-sparc patch today, I noticed another
> regression which I've bisected down to the above commit.
>
> Booting my NetBSD/OpenBSD test images with current git master causes the
> following warning to appear on the console: "WARNING: negative runtime;
> monotonic clock has gone backwards".
>
> Could this be a regression or does qemu-system-sparc make an incorrect
> assumption as to how the timer should work in this scenario?
I'm not sure -- Dmitry ?
thanks
-- PMM
[Qemu-devel] [PULL 19/28] hw/ptimer: Support "on the fly" timer mode switch, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 11/28] hw/arm/virt: Reject gic-version=host for non-KVM, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 06/28] target-arm: kvm64: set guest PMUv3 feature bit if supported, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 09/28] hw/intc/gic: RAZ/WI non-sec access to sec interrupts, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 26/28] char: get rid of qemu_char_get_next_serial, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 24/28] hw/char: QOM'ify stm32f2xx_usart model, Peter Maydell, 2016/06/06
[Qemu-devel] [PULL 07/28] hw/arm/virt: Add PMU node for virt machine, Peter Maydell, 2016/06/06