From: Gerd Hoffmann <kraxel@redhat.com>
To: Alexey Kardashevskiy <aik@ozlabs.ru>
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 09:22:25 +0200 [thread overview]
Message-ID: <1410420145.6138.7.camel@nilsson.home.kraxel.org> (raw)
In-Reply-To: <1410419467-9932-1-git-send-email-aik@ozlabs.ru>
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.
Independant of that we can move the ohci error logging to tracepoints,
so ohci emulation is silent by default.
cheers,
Gerd
next prev parent reply other threads:[~2014-09-11 7:22 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 [this message]
2014-09-11 8:18 ` Alexey Kardashevskiy
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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