From: Markus Armbruster <armbru@redhat.com>
To: "Philippe Mathieu-Daudé" <f4bug@amsat.org>
Cc: Damien Hedde <damien.hedde@greensocs.com>,
Peter Maydell <peter.maydell@linaro.org>,
Eduardo Habkost <ehabkost@redhat.com>,
QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: Resetting non-qdev children in a 3-phase reset device
Date: Sat, 24 Apr 2021 07:28:07 +0200 [thread overview]
Message-ID: <87im4cb6ag.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <3dcb8efa-8f6b-0f45-a753-cc58d3bf9855@amsat.org> ("Philippe =?utf-8?Q?Mathieu-Daud=C3=A9=22's?= message of "Sat, 24 Apr 2021 01:28:56 +0200")
Philippe Mathieu-Daudé <f4bug@amsat.org> writes:
> On 4/24/21 1:06 AM, Philippe Mathieu-Daudé wrote:
>
>> Looking at qemu_register_reset() uses I found this commit:
>>
>> commit 0c7322cfd3fd382c0096c2a9f00775818a878e13
>> Date: Mon Jun 29 08:21:10 2015 +0200
>>
>> watchdog/diag288: correctly register for system reset requests
>>
>> The diag288 watchdog is no sysbus device, therefore it doesn't get
>> triggered on resets automatically using dc->reset.
>>
>> Let's register the reset handler manually, so we get correctly notified
>> again when a system reset was requested. Also reset the watchdog on
>> subsystem resets that don't trigger a full system reset.
>>
>> Why is the reset() handler in DeviceClass and not in SysbusDeviceClass
>> if "Only sysbus devices get reset"? ...
>
> Ah, probably because the problem is generic to all busses (ISA, ...)
> and not just sysbus.
diag288 is a bus-less device. Propagating reset from the root of the
qtree to the leaves won't reach it, because the qtree contains only the
devices that plug into a qbus.
>>>> Sysbus may habe been a design mistake. It goes back the qdev design
>>>> assumption "every device plugs into exactly one bus, every bus is part
>>>> of exactly one device, and the main system bus is the root of this
>>>> tree". The assumption ceased to hold long ago, but we still have
>>>> sysbus.
next prev parent reply other threads:[~2021-04-24 5:28 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-09 18:13 Resetting non-qdev children in a 3-phase reset device Peter Maydell
2021-04-18 20:16 ` Philippe Mathieu-Daudé
2021-04-19 9:03 ` Peter Maydell
2021-04-22 13:21 ` Markus Armbruster
2021-04-22 14:20 ` Philippe Mathieu-Daudé
2021-04-23 23:06 ` Philippe Mathieu-Daudé
2021-04-23 23:28 ` Philippe Mathieu-Daudé
2021-04-24 5:28 ` Markus Armbruster [this message]
2021-04-24 13:04 ` Philippe Mathieu-Daudé
2021-04-24 13:15 ` Philippe Mathieu-Daudé
2021-04-25 18:33 ` Peter Maydell
2021-04-26 5:19 ` Markus Armbruster
2021-04-26 9:09 ` Peter Maydell
2021-04-26 9:23 ` Philippe Mathieu-Daudé
2021-04-26 9:33 ` Peter Maydell
2021-04-26 11:14 ` Philippe Mathieu-Daudé
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