Re: [PATCH] MODULE_FIRMWARE for binary firmware(s)

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On Wed, 30 Aug 2006, Sven Luther wrote:

no, at least not in the current kernel. as was mentioned earlier in this
thread the ipw2200 needs the firmware at initialization, but some others
don't need it until open. I don't know if it's even possible to re-write
the driver to do this.
Oh well, this doesn't explain why it is so, but i suppose you know what you
speak about.
I'm a user, not a developer. I know what is, but not nessasarily why, and I have
no idea how bad it would be to change.
If we want to remove it, then we put, not the module, but the firmware
itself
with some basic userspace to load it on demand in the initramfs, and this
is
reason enough to create an initramfs. The fact that the builtin device is
initialized before the initramfs is loaded seems like a bug to me, since
the
idea of the initramfs (well, one of them at least), was to initialize it
early
enough for this kind of things.
this isn't my understanding.
Indeed, in the initrd era, the ramdisk was initialized too late for this kind
of stuff, but it was one of the features of the initramfs ramdisks to
initialize it earlier, which made firmware loading possible.

my understanding is that the kernel fully initializes all built-in drivers,
then loads userspace and starts running it.
Well, there is userspace and userspace.

that userspace can be on a device that it knows how to read, or it can be
userspace on initramfs so that you can load additional modules to give you
access to the hardware that you want to run on.
Yep, but initramfs is initialized ways earlier than normal userspace.

however this is not soon enough to supply the firmware for devices like
this.
Are you sure of this ? This is somewhat contrary to what i have heard, and it
sure would make sense to be able to access the initramfs ramdisk much earlier.
I could easily be wrong about this. can someone who really knows weigh in on
this?
If on the other side, it is more important to not have an initramfs
(because
of security issues, or bootloader constraints or what not), then sure,
there
is not much choice than putting the firmware in the driver or in the kernel
directly.

But again, the initramfs is just a memory space available at the end of the
kernel, and there is no hardware-related constraint to access it which are
in
any way different from having the firmware linked in together with the
kernel,
so it is only a matter of organisation of code, as well as taking a
decision
on the above, and to act accordyingly.
if the firmware needed for any drivers compiled in was appended to the
kernel the same way that initramfs is, without requireing the other things
needed to make initrmfs useable I think that would be reasonable (bundling
them togeather as opposed to embedding the firmware in the kernel). it may
even be possible to have the firmware as files in a initramfs that contains
nothing else, and the kernel knows how to read the data directly (without
the hotplug firmware request userspace stuff)
Indeed, and it seems to me that exactly this kind of use was indeed considered
when the initramfs infrastructure was designed. Not sure about the latest bit
concerning hotplug though.
this gets back to the question of how early this early userspace is

David Lang
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