From: "Sjur Brændeland" <sjurbren@gmail.com>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>,
Ohad Ben-Cohen <ohad@wizery.com>,
Amit Shah <amit.shah@redhat.com>,
linux-kernel@vger.kernel.org,
Linus Walleij <linus.walleij@linaro.org>,
virtualization@lists.linux-foundation.org
Subject: Re: [RFC 1/2] virtio_console: Add support for DMA memory allocation
Date: Fri, 7 Sep 2012 11:24:24 +0200 [thread overview]
Message-ID: <CAJK669bqRF6WiQ8=21pEyUB565i80CeN0eniWcPBxXNLCOcxXA@mail.gmail.com> (raw)
In-Reply-To: <20120905191657.GA15868@redhat.com>
Hi Michael.
>> Not just fail to work, the kernel will panic on the BUG_ON().
>> Remoteproc gets the virtio configuration from firmware loaded
>> from user space. So this type of problem might be triggered
>> for other virtio drivers as well.
>
> how?
...
>> Even if we fix this particular problem, the general problem
>> still exists: bogus virtio declarations in remoteproc's firmware
>> may cause BUG_ON().
>
> which BUG_ON exactly?
I am afraid I have been barking up the wrong tree here.
Please ignore my previous rambling about panics related
to device features.
I hit the BUG() in virtio_check_driver_offered_feature():
First I did not declare the feature because DMA was not set:
static unsigned int features[] = {
...
#if VIRTIO_CONSOLE_HAS_DMA
VIRTIO_CONSOLE_F_DMA_MEM,
#endif
};
and then in probe I checked if the feature was supported:
virtio_has_feature(vdev, VIRTIO_CONSOLE_F_DMA_MEM)
This triggered the BUG() in virtio_check_driver_offered_feature(),
because the driver was asking for a unknown-feature.
I can get avoid this by simply checking the devices feature bits directly
instead of using virtio_has_feature().
Regards,
Sjur
next prev parent reply other threads:[~2012-09-07 9:29 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-03 13:51 [RFC 1/2] virtio_console: Add support for DMA memory allocation sjur.brandeland
2012-09-03 13:51 ` [RFC 2/2] virtio_console: Add feature to disable console port sjur.brandeland
2012-09-03 14:30 ` [RFC 1/2] virtio_console: Add support for DMA memory allocation Michael S. Tsirkin
2012-09-03 14:57 ` Sjur Brændeland
2012-09-03 20:27 ` Michael S. Tsirkin
2012-09-04 6:07 ` Rusty Russell
2012-09-05 13:00 ` Sjur Brændeland
2012-09-05 14:35 ` Michael S. Tsirkin
2012-09-05 18:15 ` Sjur Brændeland
2012-09-05 19:16 ` Michael S. Tsirkin
2012-09-07 9:24 ` Sjur Brændeland [this message]
2012-09-04 11:28 ` Sjur Brændeland
2012-09-04 13:50 ` Michael S. Tsirkin
2012-09-04 16:58 ` Sjur Brændeland
2012-09-04 18:55 ` Michael S. Tsirkin
2012-09-06 2:04 ` Rusty Russell
2012-09-06 5:27 ` Michael S. Tsirkin
2012-09-10 22:11 ` Michael S. Tsirkin
2012-09-12 6:24 ` Rusty Russell
2012-09-07 8:35 ` Sjur Brændeland
2012-09-16 9:44 ` [PATCH repost] virtio: don't crash when device is buggy Michael S. Tsirkin
2012-09-17 4:27 ` Rusty Russell
2012-09-18 22:24 ` Michael S. Tsirkin
2012-09-19 4:10 ` Rusty Russell
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