Re: [Qemu-devel] [PATCH 08/16] ahci: clear error register before NCQ cmd

2015-06-23 Thread Stefan Hajnoczi
On Mon, Jun 22, 2015 at 05:51:10PM -0400, John Snow wrote: > Or I'll just ignore this whole train of thought under the premise that > every OS alive will always send an IDENTIFY packet first, and be on my way. Yes, it's not worth worrying about at this stage when guest OSes seem to be happy with Q

Re: [Qemu-devel] [PATCH 08/16] ahci: clear error register before NCQ cmd

2015-06-22 Thread John Snow
On 06/22/2015 10:43 AM, John Snow wrote: > > > On 06/22/2015 10:38 AM, Stefan Hajnoczi wrote: >> On Fri, Jun 19, 2015 at 09:50:39PM -0400, John Snow wrote: >>> The legacy ide command execution layer will clear any errors >>> outstanding before execution, but the NCQ layer doesn't. Even on >>> s

Re: [Qemu-devel] [PATCH 08/16] ahci: clear error register before NCQ cmd

2015-06-22 Thread John Snow
On 06/22/2015 10:38 AM, Stefan Hajnoczi wrote: > On Fri, Jun 19, 2015 at 09:50:39PM -0400, John Snow wrote: >> The legacy ide command execution layer will clear any errors >> outstanding before execution, but the NCQ layer doesn't. Even on >> success, this register will remain clogged. >> >> Cle

Re: [Qemu-devel] [PATCH 08/16] ahci: clear error register before NCQ cmd

2015-06-22 Thread Stefan Hajnoczi
On Fri, Jun 19, 2015 at 09:50:39PM -0400, John Snow wrote: > The legacy ide command execution layer will clear any errors outstanding > before execution, but the NCQ layer doesn't. > Even on success, this register will remain clogged. > > Clear it out before each NCQ command so the guest can tell

[Qemu-devel] [PATCH 08/16] ahci: clear error register before NCQ cmd

2015-06-19 Thread John Snow
The legacy ide command execution layer will clear any errors outstanding before execution, but the NCQ layer doesn't. Even on success, this register will remain clogged. Clear it out before each NCQ command so the guest can tell if the error code produced after completion is meaningful or not. Si