From: Alexey Kardashevskiy <aik@ozlabs.ru>
To: Gerd Hoffmann <kraxel@redhat.com>
Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org,
Alexander Graf <agraf@suse.de>
Subject: Re: [Qemu-devel] [PATCH] ohci: Stop OHCI bus when PCI bus master is disabled
Date: Thu, 11 Sep 2014 18:18:01 +1000 [thread overview]
Message-ID: <54115AB9.8080700@ozlabs.ru> (raw)
In-Reply-To: <1410420145.6138.7.camel@nilsson.home.kraxel.org>
On 09/11/2014 05:22 PM, Gerd Hoffmann wrote:
> On Do, 2014-09-11 at 17:11 +1000, Alexey Kardashevskiy wrote:
>> When the guest performs kexec() (for example, as a part of kdump),
>> new kernel does PCI probing. As a part of it, PCI_COMMAND_MASTER
>> gets disabled which disables bus master memory region.
>> Since ohci_frame_boundary() timer is not stopped at this point
>> as OHCI device was not reset, the device tries accessing DMA memory,
>> fails and ends up in ohci_die() producing errors:
>>
>> usb-ohci: HCCA read error at 30000000
>> ohci_die: DMA error
>
> Which is the correct behavior.
>
> IMHO the kernel should stop ohci before doing kexec.
To be precise, it is kdump.
> Independant of that we can move the ohci error logging to tracepoints,
> so ohci emulation is silent by default.
That is the other way to go, yes.
--
Alexey
next prev parent reply other threads:[~2014-09-11 8:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-11 7:11 [Qemu-devel] [PATCH] ohci: Stop OHCI bus when PCI bus master is disabled Alexey Kardashevskiy
2014-09-11 7:22 ` Gerd Hoffmann
2014-09-11 8:18 ` Alexey Kardashevskiy [this message]
2014-09-11 10:15 ` Gerd Hoffmann
2014-09-11 10:30 ` Alexey Kardashevskiy
2014-09-11 10:38 ` Gerd Hoffmann
2014-09-11 11:02 ` Alexey Kardashevskiy
2014-09-12 4:09 ` Alexey Kardashevskiy
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