Date: Wed, 27 Feb 2008 18:24:27 -0600
From: Robert Hancock <hancockr@shaw.ca>
Subject: Re: [PATCH] sata_nv: fix nmi intr or system hanging in rhel4u6 adma.
In-reply-to: <15F501D1A78BD343BE8F4D8DB854566B1BFE2AE7@hkemmail01.nvidia.com>
To: Kuan Luo <kluo@nvidia.com>
Cc: Jeff Garzik <jeff@garzik.org>, linux-kernel <linux-kernel@vger.kernel.org>,
       Tejun Heo <htejun@gmail.com>, Peer Chen <pchen@nvidia.com>,
       Allen Martin <AMartin@nvidia.com>
Message-id: <47C5FF3B.2000000@shaw.ca>
MIME-version: 1.0
Content-type: text/plain; charset=ISO-8859-1; format=flowed
Content-transfer-encoding: 7bit
References: <15F501D1A78BD343BE8F4D8DB854566B1BFE2AE5@hkemmail01.nvidia.com>
 <47C42534.1090107@shaw.ca> <47C43E27.5070700@garzik.org>
 <15F501D1A78BD343BE8F4D8DB854566B1BFE2AE7@hkemmail01.nvidia.com>
User-Agent: Thunderbird 2.0.0.9 (Windows/20071031)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1927
Lines: 48

Kuan Luo wrote:
> Jeff wrote:
>> robert worte:
>>> This is basically avoiding switching into register mode, 
>> right? I don't 
>>> think this is a very good solution as the point of the 
>> tf_read function 
>>> is that it's supposed to read the taskfile provided by the drive to 
>>> diagnose the error, so not doing this isn't a good thing.
>> Agree with this analysis -- if ->tf_read() is being called, then 
>> obviously the core wants a current copy of the device's ATA registers.
>>
>> It is not a good solution to simply avoiding returning 
>> meaningful data, 
>> because -- as Robert notes -- we need tf_read for analysis.
>>
>> 	Jeff
>>
> 
> The driver got one error : "nv_adma_check_cpb: CPB 0, flags=0x11". The
> code entered ata_port_abort -> ata_qc_complete
> -> fill_result_tf->nv_adma_tf_read.
> 
> Firstly, nv_adma_register_mode failed, showing the below messages:
> timeout waiting for ADMA IDLE, stat=0x440
> timeout waiting for ADMA LEGACY, stat=0x440
> 
> Then enter ata_tf_read function. 
> I found the system hung at tf->hob_nsect = ioread8(ioaddr->nsect_addr);
> Sometimes the screen showed "
> CPU0: Machin check Exception 0000000000000004
> Bank 4:b200000000070f0f
> kernel panic -not syncing: CPU Context corrupt.
> "
> If nv_adma_register_mode failed, the reg result should be not
> meaningful. 
> I don't know why the systm hung.

By the way, this MCE indicates that the CPU integrated northbridge got a 
watchdog error indicating that a bus transaction timed out (presumably 
on the HyperTransport link). This likely indicates that the chipset 
failed to respond to a CPU read of that register. Obviously this is 
something we want to avoid causing..
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/