linux-firmware tree

linux-firmware tree

[Mike Waychison]

Hi David,

I'm trying to understand the purpose of the linux-firmware tree.
Forgive me if this is a stupid question, but the only information
about it I could find was your original post back in 2008:
https://lwn.net/Articles/294308/

Will the Linux kernel sources always continue to have the firmware
blobs and the linux-firmware tree is only for those users of distros
that strip the firmware out?

I'm trying to understand if there would ever be a need to integrate
the linux-firmware tree into our builds (we build a derivative of
Linus' tree).

Thanks,

Mike Waychison

Re: linux-firmware tree

[David Woodhouse]

On Mon, 2011-05-02 at 19:57 +0100, Mike Waychison wrote:
> Hi David,
> 
> I'm trying to understand the purpose of the linux-firmware tree.
> Forgive me if this is a stupid question, but the only information
> about it I could find was your original post back in 2008:
> https://lwn.net/Articles/294308/
> 
> Will the Linux kernel sources always continue to have the firmware
> blobs and the linux-firmware tree is only for those users of distros
> that strip the firmware out?

No, the legacy firmware images from the kernel tree are going to be
removed. They were only kept for backward compatibility.

The linux-firmware tree has a lot of things that were never included in
the kernel source; no *new* firmware images are being (or at least
should be) added to the kernel source itself.

Everyone should be using the linux-firmware tree by now.

-- 
dwmw2

Re: linux-firmware tree

[Mike Waychison]

On Mon, May 2, 2011 at 12:38 PM, David Woodhouse <dwmw2@infradead.org> wrote:
> On Mon, 2011-05-02 at 19:57 +0100, Mike Waychison wrote:
>> Hi David,
>>
>> I'm trying to understand the purpose of the linux-firmware tree.
>> Forgive me if this is a stupid question, but the only information
>> about it I could find was your original post back in 2008:
>> https://lwn.net/Articles/294308/
>>
>> Will the Linux kernel sources always continue to have the firmware
>> blobs and the linux-firmware tree is only for those users of distros
>> that strip the firmware out?
>
> No, the legacy firmware images from the kernel tree are going to be
> removed. They were only kept for backward compatibility.
>
> The linux-firmware tree has a lot of things that were never included in
> the kernel source; no *new* firmware images are being (or at least
> should be) added to the kernel source itself.
>
> Everyone should be using the linux-firmware tree by now.

Fair enough.  We haven't actually hit a case where the firmware
required by any of the drivers we use isn't already present in the
tree.

I'm trying to figure out how we could ship firmware blobs on our
systems going forward.  Currently, we let firmware get installed to
our install root via the modules_install target, and then package up
the install root.  If drivers are going to request firmware blobs from
userland without them being picked up in-tree by
fw-shipped-$(CONFIG_FOO), we'll need to know at build time which
firmware blobs to package up.

I don't see anything in the build (looking at scripts/Makefile.fwinst
in particular) that allows the build to enumerate out-of-tree firmware
files required by drivers.  Do you have any thoughts on how this could
be enumerated? (if it isn't already?)


The alternative would be to ship the whole of the linux-firmware tree
on every machine we have, but that seems like a bad idea as it is only
going to grow with time and we don't have the MiB budget for such a
thing.

Re: linux-firmware tree

[David Woodhouse]

On Mon, 2011-05-02 at 14:40 -0700, Mike Waychison wrote:
> I don't see anything in the build (looking at scripts/Makefile.fwinst
> in particular) that allows the build to enumerate out-of-tree firmware
> files required by drivers.  Do you have any thoughts on how this could
> be enumerated? (if it isn't already?)

Using the MODULE_FIRMWARE tags of the drivers which are built.

This is actually the reason we haven't removed the legacy firmware from
the source tree yet; it's waiting for me to implement that bit.

It shouldn't be hard to post-process the modules and list the firmware
blobs that they reference. We'd just want to make it do the same for
built-in drivers too.

-- 
dwmw2

Re: linux-firmware tree

[Valdis.Kletnieks]

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On Mon, 02 May 2011 14:40:33 PDT, Mike Waychison said:

> I don't see anything in the build (looking at scripts/Makefile.fwinst
> in particular) that allows the build to enumerate out-of-tree firmware
> files required by drivers.  Do you have any thoughts on how this could
> be enumerated? (if it isn't already?)

MODULE_FIRMWARE tags in the drivers, combined with (possibly)
the CONFIG_EXTRA_FIRMWARE and CONFIG_EXTRA_FIRMWARE_DIR
Kconfig variables if the needed bits aren't in /lib/firmware?

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