netdev - Re: 2.6.20-rc7: known regressions (v2) (part 1)

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Date:	Sat, 3 Feb 2007 18:20:08 -0500
From:	"Adam Kropelin" <akropel1@...hester.rr.com>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>,
	"Auke Kok" <auke-jan.h.kok@...el.com>
Cc:	"Adrian Bunk" <bunk@...sta.de>,
	"Linus Torvalds" <torvalds@...ux-foundation.org>,
	"Andrew Morton" <akpm@...ux-foundation.org>,
	"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
	<jgarzik@...ox.com>, <alan@...rguk.ukuu.org.uk>,
	"Allen Parker" <parker@...hunt.com>, <jesse.brandeburg@...el.com>,
	<gregkh@...e.de>, <linux-pci@...ey.karlin.mff.cuni.cz>,
	<netdev@...r.kernel.org>
Subject: Re: 2.6.20-rc7: known regressions (v2) (part 1)

Eric W. Biederman wrote:
> Auke Kok <auke-jan.h.kok@...el.com> writes:
>
>> maybe I've been unclear, but here's how e1000 detects link changes:
>>
>> 1) by checking every 2 seconds in the watchdog by reading PHY
>> registers 2) by receiving an interrupt from the NIC with the LSI bit
>> in the interrupt control register
>>
>> if the link is down to start with, the watchdog will obviously spot
>> a 'link up' change since it doesn't use any interrupts.
>>
>> The link interrupt (LSI) is a generic interrupt that comes over the
>> same vector (be it MSI or not) as RX interrupts, and in your case
>> doesn't arrive at all, which should be demonstrateable if you set
>> e.g. the watchdog interval to 30 seconds and unplug the cable - the
>> driver won't spot the link change until the watchdog fires a lot
>> later than you unplugged the cable.
>>
>>> The behavior I observe on 2.6.19 is better than 2.6.20-rc7. Link
>>> status interrupts seem to work but rx/tx does not. A few more
>>> details here:
>>>
>> <http://www.kroptech.com/~adk0212/mailimport/showmsg.php?msg_id=3339092450&db_name=linux_kernel>
>
> Can I get the corresponding lspci -xxx output.  I suspect the BIOS
> did not program the hypertransport MSI mapping capabilities correctly.
> All it has to do is set the enable but still, occasionally BIOS
> writers miss the most amazing things.

Here you go. This is from 2.6.20-rc7.

--Adam

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