From: linux@roeck-us•net (Guenter Roeck)
To: linux-arm-kernel@lists•infradead.org
Subject: [Qemu-devel] SCSI bus failures with qemu-arm in kernel 3.8+
Date: Thu, 15 Aug 2013 15:18:50 -0700 [thread overview]
Message-ID: <520D53CA.6040807@roeck-us.net> (raw)
In-Reply-To: <CAFEAcA-ALD+dDWAB+Rd1V+TXQLYGe-qRKC0uFUP0Bt2SGfKDRg@mail.gmail.com>
On 08/15/2013 02:49 PM, Peter Maydell wrote:
> On 15 August 2013 21:50, Guenter Roeck <linux@roeck-us•net> wrote:
>> On Thu, Aug 15, 2013 at 07:05:22PM +0100, Peter Maydell wrote:
>>> It needs to go in the same patch, because a kernel with the fixed
>>> irq remapping must also tell QEMU it is fixed; if you split the
>>> two then at the point between the two patches the kernel is
>>> broken for bisection purposes.
>>>
>> Thinking about it - is that really true ? My image with the
>> patch applied works just fine under qemu 1.5.2, and unless
>> I am missing something it won't work with qemu 1.4 anyway.
>> So what exactly is broken ?
>
> You're OK unless the kernel happens to pick the same interrupt
> number to write to PCI_INTERRUPT_LINE as one of the previous
> broken kernel versions did (in which case QEMU will incorrectly
> assume you're a broken kernel). This can't happen with the way
> the kernel is currently picking interrupt numbers (ie with a
> straightforward relationship between h/w irqs and values written),
> but as I understand from Arnd there is a plan to move to a
> different approach ("sparse irqs") at which point this won't hold:
> http://lists.gnu.org/archive/html/qemu-devel/2013-03/msg04579.html
> So it's better for the kernel to make sure it gets the
> behaviour it wants rather than getting unpleasant surprises
> later.
>
But doesn't that mean that there is _currently_ no problem ? If so,
we can introduce the additional code when the problem really shows up.
Being Preemptive is good, but if it is not really needed today
I would rather have today's problems resolved and bother about tomorrow's
when they show up.
Guenter
next prev parent reply other threads:[~2013-08-15 22:18 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-11 15:54 SCSI bus failures with qemu-arm in kernel 3.8+ Guenter Roeck
2013-08-11 22:04 ` Russell King - ARM Linux
2013-08-12 0:40 ` Guenter Roeck
2013-08-12 16:24 ` [Qemu-devel] " Peter Maydell
2013-08-12 16:45 ` Russell King - ARM Linux
2013-08-12 17:33 ` Peter Maydell
2013-08-12 20:06 ` Russell King - ARM Linux
2013-08-12 20:49 ` Peter Maydell
2013-08-12 21:21 ` Russell King - ARM Linux
2013-08-12 21:36 ` Peter Maydell
2013-08-12 22:12 ` Russell King - ARM Linux
2013-08-12 22:48 ` Guenter Roeck
2013-08-12 23:04 ` Guenter Roeck
2013-08-14 10:33 ` Russell King - ARM Linux
2013-08-14 12:44 ` Peter Maydell
2013-08-14 12:49 ` Russell King - ARM Linux
2013-08-14 12:56 ` Peter Maydell
2013-08-14 14:41 ` Guenter Roeck
2013-08-12 17:48 ` Peter Maydell
2013-08-13 8:37 ` Rob Landley
2013-08-13 9:12 ` Peter Maydell
2013-08-13 11:30 ` Russell King - ARM Linux
2013-08-13 3:40 ` Guenter Roeck
2013-08-15 16:45 ` Peter Maydell
2013-08-15 17:54 ` Guenter Roeck
2013-08-15 18:05 ` Peter Maydell
2013-08-15 18:39 ` Guenter Roeck
2013-08-15 20:50 ` Guenter Roeck
2013-08-15 21:49 ` Peter Maydell
2013-08-15 22:18 ` Guenter Roeck [this message]
2013-08-15 22:23 ` Peter Maydell
2013-08-15 23:25 ` Guenter Roeck
2013-08-19 15:26 ` Guenter Roeck
2013-08-12 19:02 ` Paul Gortmaker
2013-08-12 20:58 ` Peter Maydell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=520D53CA.6040807@roeck-us.net \
--to=linux@roeck-us$(echo .)net \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox