Linux-libre-4.15 and the NVMe module

Linux-libre-4.15 and the NVMe module

[Mark H Weaver]

Hello Guix,

I've pushed a new 'kernel-updates' branch that includes the update to
linux-libre-4.15, and asked Hydra to build it.  However, I haven't yet
pushed this to 'master' because of a complication.

At present, all of our kernel configurations have CONFIG_BLK_DEV_NVME=m
which results in an "nvme.ko" module, and this module is included in the
list of modules to be copied to our 'base-initrd' and loaded during
early boot.

Unfortunately, it seems that in linux-libre-4.15, we must now have
CONFIG_BLK_DEV_NVME=y (built-in) if we wish to keep CONFIG_NVM=y
(Open-Channel SSD target support), which we've had enabled in our kernel
configurations since 4.4.  CONFIG_NVM cannot be made modular, and in
4.15 it now depends on CONFIG_BLK_DEV_NVME=y.

Since I don't see a nice way in our current 'base-initrd' implementation
to conditionally include "nvme.ko" depending on the kernel
configuration, I simply removed "nvme.ko" from the list of modules, and
changed all of our kernel configurations to have CONFIG_BLK_DEV_NVME=y.

While I was at it, I updated our older kernel configurations to the
current point releases, using "make oldconfig".  My main motivation for
doing this was to explicitly show in our config files that we've enabled
the mitigations for meltdown and spectre.

Any comments on this approach?  Other suggestions?

      Mark

Re: Linux-libre-4.15 and the NVMe module

[ng0]

Hi,

On Mon, 29 Jan 2018, Mark H Weaver <mhw@netris.org> wrote:
> Hello Guix,
>
> I've pushed a new 'kernel-updates' branch that includes the update to
> linux-libre-4.15, and asked Hydra to build it.  However, I haven't yet
> pushed this to 'master' because of a complication.
>
> At present, all of our kernel configurations have CONFIG_BLK_DEV_NVME=m
> which results in an "nvme.ko" module, and this module is included in the
> list of modules to be copied to our 'base-initrd' and loaded during
> early boot.

Oh, good that you've looked deeper into this. I planned to when
the rc's started showing this problem but didn't really follow-up
to it.

> Unfortunately, it seems that in linux-libre-4.15, we must now have
> CONFIG_BLK_DEV_NVME=y (built-in) if we wish to keep CONFIG_NVM=y
> (Open-Channel SSD target support), which we've had enabled in our kernel
> configurations since 4.4.  CONFIG_NVM cannot be made modular, and in
> 4.15 it now depends on CONFIG_BLK_DEV_NVME=y.
>
> Since I don't see a nice way in our current 'base-initrd' implementation
> to conditionally include "nvme.ko" depending on the kernel
> configuration, I simply removed "nvme.ko" from the list of modules, and
> changed all of our kernel configurations to have CONFIG_BLK_DEV_NVME=y.
>
> While I was at it, I updated our older kernel configurations to the
> current point releases, using "make oldconfig".  My main motivation for
> doing this was to explicitly show in our config files that we've enabled
> the mitigations for meltdown and spectre.
>
> Any comments on this approach?  Other suggestions?
>
>       Mark
>
>

I think in general it's okay. I'm still rebuilding my server with
the patches taken from your branch. I suspect not to run into any
problems with it, and skipping the commits they looked good to me.

Of course I can only test for x86, not i686 or aarch64

Thanks!
-- 
ng0 :: https://ea.n0.is
A88C8ADD129828D7EAC02E52E22F9BBFEE348588 :: https://ea.n0.is/keys/

Re: Linux-libre-4.15 and the NVMe module

[Mark H Weaver]

Mark H Weaver <mhw@netris.org> writes:
> I've pushed a new 'kernel-updates' branch that includes the update to
> linux-libre-4.15, and asked Hydra to build it.

I went ahead and pushed these commits to master, following a successful
evaluation on Hydra and some additional testing on my systems.

      Mark

Re: Linux-libre-4.15 and the NVMe module

[Danny Milosavljevic]

Hi Mark,

On Mon, 29 Jan 2018 09:18:17 -0500
Mark H Weaver <mhw@netris.org> wrote:

> Unfortunately, it seems that in linux-libre-4.15, we must now have
> CONFIG_BLK_DEV_NVME=y (built-in) if we wish to keep CONFIG_NVM=y
> (Open-Channel SSD target support), which we've had enabled in our kernel
> configurations since 4.4.  CONFIG_NVM cannot be made modular, and in
> 4.15 it now depends on CONFIG_BLK_DEV_NVME=y.

I wonder whether that's a regression or on purpose...

> Since I don't see a nice way in our current 'base-initrd' implementation
> to conditionally include "nvme.ko" depending on the kernel
> configuration, I simply removed "nvme.ko" from the list of modules, and
> changed all of our kernel configurations to have CONFIG_BLK_DEV_NVME=y.

I think that's fine for the time being.

That said, it would be nice if we extended our base-initrd implementation to
take a list of modules to try to copy, and to skip each which doesn't exist.

It would make the initrds more reusable and I don't see a downside if we
supported both this new list of modules and the existing list of modules.

> While I was at it, I updated our older kernel configurations to the
> current point releases, using "make oldconfig".  My main motivation for
> doing this was to explicitly show in our config files that we've enabled
> the mitigations for meltdown and spectre.

Good idea.

Re: Linux-libre-4.15 and the NVMe module

[Ludovic Courtès]

Mark H Weaver <mhw@netris.org> skribis:

> Mark H Weaver <mhw@netris.org> writes:
>> I've pushed a new 'kernel-updates' branch that includes the update to
>> linux-libre-4.15, and asked Hydra to build it.
>
> I went ahead and pushed these commits to master, following a successful
> evaluation on Hydra and some additional testing on my systems.

Excellent, thank you!

Ludo’.