Re: [PATCH 17/17] hw/block/nvme: change controller pci id

[Klaus Jensen]

On Sep  7 10:36, Philippe Mathieu-Daudé wrote:
> On 9/7/20 9:23 AM, Klaus Jensen wrote:
> > On Sep  7 04:28, Philippe Mathieu-Daudé wrote:
> >> +David in case
> >>
> >> On 9/4/20 4:19 PM, Klaus Jensen wrote:
> >>> From: Klaus Jensen <k.jensen@samsung.com>
> >>>
> >>> There are two reasons for changing this:
> >>>
> >>>   1. The nvme device currently uses an internal Intel device id.
> >>>
> >>>   2. Since commits "nvme: fix write zeroes offset and count" and "nvme:
> >>>      support multiple namespaces" the controller device no longer has
> >>>      the quirks that the Linux kernel think it has.
> >>>
> >>>      As the quirks are applied based on pci vendor and device id, change
> >>>      them to get rid of the quirks.
> >>>
> >>> To keep backward compatibility, add a new 'x-use-intel-id' parameter to
> >>> the nvme device to force use of the Intel vendor and device id. This is
> >>> off by default but add a compat property to set this for 5.1 machines
> >>> and older.
> >>
> >> So now what happens if you start a 5.1 machine with a recent kernel?
> >> Simply the kernel will use unnecessary quirks, or are there more
> >> changes in behavior?
> >>
> > 
> > Yes, the kernel will then just apply unneccesary quirks, these are:
> > 
> >   1. NVME_QUIRK_IDENTIFY_CNS which says that the device does not support
> >      anything else than values 0x0 and 0x1 for CNS (Identify Namespace and
> >      Identify Namespace). With multiple namespace support, this just
> >      means that the kernel will "scan" namespaces instead of using
> >      "Active Namespace ID list" (CNS 0x2).
> > 
> >   2. NVME_QUIRK_DISABLE_WRITE_ZEROES. The nvme device started out with a
> >      broken Write Zeroes implementation which has since been fixed in
> >      commit 9d6459d21a6e ("nvme: fix write zeroes offset and count").
> 
> OK thanks. Can you amend that information in the commit
> description please?
> 

Yes, absolutely.

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