How to get rid of unused data in LKM

How to get rid of unused data in LKM

[Matthias Fuchs]

Hi,

I am writing a LKM that contains a huge constant array of data that is used
as firmware for a PCI card that is connected to the system where the LKM is loaded.

The module_init function writes the constant data array into the PCI card's RAM and triggers
a CPU on that card to jump to the firmware code. This works fine.

But after doing so, the firmware data is still wasting kernel memory on the host system
and is not used anymore.
How can I free that memory ? Is there a better way to handle that data ?
Currently I have a global variable in my module code:

unsigned char firmware[] = { ..., .... ,.... about 1.4 Meg, ...}

The firmware data (about 1.4 Meg) must be linked with the LKM.

Any idea ?

Matthias


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Re: How to get rid of unused data in LKM

[Wolfgang Denk]

In message <3D3E91E6.4000500@esd-electronics.com> you wrote:
>
> I am writing a LKM that contains a huge constant array of data that is used
> as firmware for a PCI card that is connected to the system where the LKM is loaded.
>
> The module_init function writes the constant data array into the PCI card's RAM and triggers
> a CPU on that card to jump to the firmware code. This works fine.

Why don't you load the firmware using some  ioctl()  _after_  loading
the module?

> But after doing so, the firmware data is still wasting kernel memory on the host system
> and is not used anymore.
> How can I free that memory ? Is there a better way to handle that data ?

If you really think you must link the data with the  module:  Declare
it using "__initdata" ?

Wolfgang Denk

--
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
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Re: How to get rid of unused data in LKM

[John Tyner]

> > But after doing so, the firmware data is still wasting kernel memory on the host system
> > and is not used anymore.
> > How can I free that memory ? Is there a better way to handle that data ?
>
> If you really think you must link the data with the  module:  Declare
> it using "__initdata" ?

I was under the impression that data like this is not thrown away when
compiled as a module... only when compiled directly into the kernel. Is
this not true?

I think Wolfgang's ioctl idea is a much better way to go in this case.


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