Re: [PATCH v3 2/2] nvme: initialize known effects to set ns_mgmt NCC and ns_attach NIC

[Keith Busch <kbusch@kernel.org>]

On Wed, Apr 29, 2026 at 03:08:59PM +0900, Tokunori Ikegami wrote:
> On 2026/04/28 15:51, Keith Busch wrote:
> > I suppose that's why the "known_effects" exists, but it'd be
> > dissappointing if we really need this. The other opcodes in there
> > existed before the Command Effects Log was created, so understandable
> > that controllers may not implement it. But NS management/attach were
> > introduced after the log, and there is also the AEN that the driver
> > could rescan on receipt, so it's doubly bad if a controller
> > implementation really needs this.
> 
> Just rechecked the specification again then the log page identifier:
> commands supported and effects mentioned is optional for NVM express
> revision 1.4 and earlier then for the older controller the changes not bad I
> think.

Yes, but the namespace management commands are also optional, so it
sounds weird to me for an implementation to choose to support the
optional command that's more difficult to do and skip the easy log page
that advertises support for it.

> By the way about the scan_work executions for the command effects log and
> AEN I thought it is better to be handled only once but I do not have an
> actual idea for the exclusive control.

You can attach namespaces to controllers driven by a different host, so
the AEN is the only way to trigger a rescan in such a scenario without
admin intervention. An extra scan_work is otherwise harmless, I don't
see a particular need to introduce a mechanism to avoid it.