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Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices |
Date: |
Fri, 20 Aug 2010 18:14:19 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) |
Anthony Liguori <address@hidden> writes:
> On 08/20/2010 10:47 AM, Markus Armbruster wrote:
>> Alex Williamson<address@hidden> writes:
>>
>>
>>> On Fri, 2010-08-20 at 11:00 +0200, Markus Armbruster wrote:
>>>
>>>> Alex Williamson<address@hidden> writes:
>>>>
>>>>
>>>>> Several devices rely on their reset() function being called to
>>>>> initialize device state, e1000 and rtl8139 in particular. When
>>>>> the device is hot added, the reset doesn't occur, often leaving
>>>>> the device in an unusable state. Adding a call to reset() after
>>>>> init() for hotplugged devices puts the device in the expected
>>>>> state for the guest.
>>>>>
>>>>> Signed-off-by: Alex Williamson<address@hidden>
>>>>> ---
>>>>>
>>>>> 0.13 candidate?
>>>>>
>>>>> hw/qdev.c | 3 +++
>>>>> 1 files changed, 3 insertions(+), 0 deletions(-)
>>>>>
>>>>> diff --git a/hw/qdev.c b/hw/qdev.c
>>>>> index e99c73f..b156272 100644
>>>>> --- a/hw/qdev.c
>>>>> +++ b/hw/qdev.c
>>>>> @@ -278,6 +278,9 @@ int qdev_init(DeviceState *dev)
>>>>> qdev_free(dev);
>>>>> return rc;
>>>>> }
>>>>> + if (dev->hotplugged) {
>>>>> + qdev_reset(dev);
>>>>> + }
>>>>> qemu_register_reset(qdev_reset, dev);
>>>>> if (dev->info->vmsd) {
>>>>> vmstate_register_with_alias_id(dev, -1, dev->info->vmsd, dev,
>>>>>
>>>> qdev_reset() isn't necessary when !dev->hotplugged, because then
>>>> qemu_system_reset() will run shortly, which will call qdev_reset().
>>>> Correct?
>>>>
>>> Yes, exactly.
>>>
>> Hmm. "qdev_init() automatically calls qdev_reset() if hotplug" feels
>> needlessly complicated. I'd prefer qdev_init() to call it always or
>> never.
>>
>> If "always", we reset twice for cold-plug. Is that bad?
>>
>> If "never", we need to reset somewhere else for hot-plug. What about
>> do_device_add()?
>>
>
> The real problem is how we do reset. We shouldn't register a reset
> handler for every qdev device but rather register a single reset
> handler that walks the device tree and calls reset on every reachable
> device.
>
> Then we can always call reset in init() and there's no need to have a
> dev->hotplugged check. The qdev device tree reset handler should not
> be registered until *after* we call qemu_system_reset() after creating
> the device model which will ensure that we don't do a double reset.
Fine with me.
But we need to merge something short term (pre 0.13) to fix hot plug of
e1000 et al. Use Alex's patch as such a stop-gap?
- [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Alex Williamson, 2010/08/03
- [Qemu-devel] Re: [PATCH] qdev: Reset hotplugged devices, Glauber Costa, 2010/08/03
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Markus Armbruster, 2010/08/20
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Alex Williamson, 2010/08/20
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Markus Armbruster, 2010/08/20
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Anthony Liguori, 2010/08/20
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices,
Markus Armbruster <=
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Anthony Liguori, 2010/08/20
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Alex Williamson, 2010/08/20
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Markus Armbruster, 2010/08/21
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Anthony Liguori, 2010/08/21
- [Qemu-devel] Re: [PATCH] qdev: Reset hotplugged devices, Paolo Bonzini, 2010/08/23
- [Qemu-devel] Re: [PATCH] qdev: Reset hotplugged devices, Anthony Liguori, 2010/08/23
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Isaku Yamahata, 2010/08/24
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Anthony Liguori, 2010/08/25
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Isaku Yamahata, 2010/08/25
- Re: [Qemu-devel] [PATCH] qdev: Reset hotplugged devices, Anthony Liguori, 2010/08/25