Re: [PATCH] sata_nv: fix nmi intr or system hanging in rhel4u6 adma.

[Robert Hancock]

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..
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