Re: [PATCH v1 1/4] xprtrdma: Remove support for FMR memory registration

[Leon Romanovsky <leon@kernel.org>]

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On Mon, Nov 19, 2018 at 12:52:10PM -0800, Bart Van Assche wrote:
> On Mon, 2018-11-19 at 21:09 +0200, Leon Romanovsky wrote:
> > The more accurate question is "how many customers ... use latest,
> > upstream kernel?"
>
> Hi Leon,
>
> If this would not be clear: I am in favor of removing kernel drivers that
> are no longer in use. Recently I supported a proposal to remove the SCSI
> OSD driver from the kernel tree because that driver
> probably has not been
> used by anyone in the past five years.
>
> But I think that kernel drivers that are still in use should stay in the
> kernel tree, no matter which version is in use. Since the Linux kernel ABI
> is backwards compatible, with every Linux distro it is possible to replace
> the Linux kernel that was provided by the Linux distributor with a more
> recent upstream kernel. I think it would be a very unpleasant surprise for
> people who use one of the RDMA adapters that only support FMR if they would
> test a more recent kernel and if they would notice that its driver has been
> removed.

Bart,

I know the theory behind promises to work on old HW, but the reality
that no one really tests latest kernels on those devices.

This article complains about it too:
https://lwn.net/Articles/769468/


Thanks

>
> Bart.

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