Re: [Xen-devel] HVM with old kernel(rh5.1) assigned device resume failure because of restore sequence

[Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>]

On Fri, 17 Apr 2009 10:32:31 +0800
"Ke, Liping" <liping.ke@xxxxxxxxx> wrote:

> Older kernel(before 2.6.18 in rh5.1) cmd register is restored before Bar 
> register,
> it will cause qemu passthrough pt_mapping_bars failure.
> (In qemu, pt_bar_mappings is done in pt_cmd_reg_write. pt_bar_reg_write is 
> not performed
> yet, then pt_bar_mappings can't map the correct address)
> Latest kernel (after 2.6.2X) has no such problem. (When do pt_bar_mapping in 
> pt_cmd_reg_write,
> pt_bar_reg_write is already done).
> 
> I pasted corrected Qemu(2.6.29) log (line 660) and uncorrected Qemu(rh5.1) 
> Log (Line 554)
> and add [ criping XXX] comments for your reference.
> For supporting old kernel, could we consider to change the pt_bar_mappings 
> sequence in Qemu?
> We'd like to have your opinions first.

The following modification is required.

  When pt_bar_reg_write is called, it should call pt_bar_mapping if
  memory space bit or IO space bit in command register is '1'.

As a result IO/memory resource is mapped at the correct address.

Thanks,
--
Yuji Shimada


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