Re: [Xen-devel] AHCI question

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Mon, Nov 22, 2010 at 09:51:26AM -0500, Kamala Narasimhan wrote:
> I am writing a polled mode Xen AHCI driver to collect some minimal

What is a 'Xen AHCI' driver?

> information after a system crash.  As dom0 would have initialized and
> used the HBA before we enter the crashing code path, I am not doing
> any kind of device initialization within the Xen AHCI driver.  I am
> also not setting up interrupts etc. as the driver is used in polled
> mode.  I simply map the abar and other memory regions associated with
> the device that dom0 has already setup and write to it/read from it as
> needed.
> 
> After a crash, within the Xen AHCI driver I am able to get to the pci
> space for the device, get valid HBA registers, mapping etc. works but
> the HBA does not respond back after I issue a command for execution.
> In specific, after I set the port x command issue register (pxci) for
> the free slot, that slot is not getting cleared as it should after a
> command execution.
> 
> As an experiment to see if anything at all works with respect to
> setting/resetting port registers, I simply decided to stop/start the
> HBA command engine by setting the ST bit in the command register
> (PxCMD) to 0 and then checking if CR, FR bit etc. in PxCMD are reset
> by HBA after a ST reset but they remain set.
> 
> I am hoping someone with AHCI experience might be able to shed some
> light as to why the HBA is not responding as it should.  Thanks.
> 
> Kamala
> 
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