Re: [Xen-devel] [PATCH] Improve the current FLR logic

["Neo Jia" <neojia@xxxxxxxxx>]

Yuji,

Could you show me how to use the hotplug method to restore the
register? Also, in the current implementation, we just read 4 bytes
each time and write them from 0 to 256 - 4. Will this cause any side
effect?

Thanks,
Neo

On Thu, Jul 17, 2008 at 2:33 AM, Yuji Shimada
<shimada-yxb@xxxxxxxxxxxxxxx> wrote:
> On Sat, 12 Jul 2008 20:37:34 +0800
> "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote:
>
>> I'd like to ask for your comments, and test feedbacks. Thank you very
>> much!
>
> There is a problem with the device reconfiguring logic. xend saves all
> Configuration Register's values before reset. And xend writes the
> values to the registers after reset. This means the resister's values
> which are configured by guest software are restore. Guest software
> setting should be cleared.
>
> I think the following Configuration Resister should be reconfigured to
> correct values after reset. And other registers should not be
> reconfigured after reset if there is no reason.
>
> - It is necessary to write the base address of the resource allocated
>  by the dom0 kernel to the following resister.
>    - Base Address Register
>
> - When dom0 starts, the values configured by firmware should be saved,
>  and the values should be written to the following resisters after
>  reset. The reason is that firmware configures them to archive system
>  specific functions. Especially, the registers relating error reporting
>  are configured to collect error information. If this configured values
>  is changed, some functions might be lost.
>  Instead of save/restore, it is good way to write the value from _HPX
>  method to registers, I think. _HPX method returns the value to write
>  to registers.
>    - Cache-line size Register
>    - Latency timer Register
>    - Enable SERR Bit/Enable PERR Bit in Device Control Register
>    - Uncorrectable Error Mask Register
>    - Uncorrectable Error Severity Register
>    - Correctable Error Mask Register
>    - Advanced Error Capabilities and Control Register
>    - Device Control Register
>    - Link Control Register
>    - Secondary Uncorrectable Error Severity Register
>    - Secondary Uncorrectable Error Mask Register
>    - Device Control 2 Register
>    - Link Control 2 Register
>
> - The following resister should be configured to "0".
>    - PME Enable Bit/PME Status Bit in PCI Power Management
>      Control/Status Register
>
> I would like to discuss this logic more.
>
> Thanks.
>
> --
> Yuji Shimada
>
>
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>



-- 
I would remember that if researchers were not ambitious
probably today we haven't the technology we are using!

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