On Sep 7 10:58, Klaus Jensen wrote: > 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.jen...@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.
By the way. Is it correct use of an 'x-' parameter here - since it is something that we might remove in the future? I was unable to find any documentation on the purpose of the 'x-' prefix, but I was guessing it was for stuff like this.
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