Re: [PATCH v2 0/3] Convert sparc devices to new ptimer API

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

On 10/24/19 8:04 PM, Mark Cave-Ayland wrote:
> On 24/10/2019 13:19, Peter Maydell wrote:
> 
>> On Mon, 21 Oct 2019 at 14:43, Peter Maydell <peter.maydell@linaro.org> wrote:
>>>
>>> This patchset converts the devices used by sparc machines to the new
>>> ptimer API.
>>>
>>> Currently the ptimer design uses a QEMU bottom-half as its mechanism
>>> for calling back into the device model using the ptimer when the
>>> timer has expired.  Unfortunately this design is fatally flawed,
>>> because it means that there is a lag between the ptimer updating its
>>> own state and the device callback function updating device state, and
>>> guest accesses to device registers between the two can return
>>> inconsistent device state. This was reported as a bug in a specific
>>> timer device but it's a problem with the generic ptimer code:
>>> https://bugs.launchpad.net/qemu/+bug/1777777
>>>
>>> The updates to the individual ptimer devices are straightforward:
>>> we need to add begin/commit calls around the various places that
>>> modify the ptimer state, and use the new ptimer_init() function
>>> to create the timer.
>>>
>>> Changes v1->v2:
>>>   * patches 2 and 3 are the old 1 and 2 and have been reviewed
>>>   * patch 1 is new and removes a pointless NULL check; without
>>>     this we'd probably have got Coverity errors when patch 3
>>>     added a use of t->timer before the check for it being NULL
>>
>> I'm going to apply these to target-arm.next; I know they haven't
>> been on list long but the change since v1 is only minor and
>> they've all been reviewed.
> 
> Thanks Peter! Not sure if you saw my Tested-by tag last week for the slavio (sun4m)
> parts, but there were no obvious regressions that I could see under qemu-system-sparc.

This was on v1:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg653861.html