On 14 Mar 2002, Oleg Goldshmidt wrote:
>
> Can I use math functions (e.g. exp log) in a Linux kernel module in a
> transparent way? It does not seem to be trivial, and I have not found
> any useful docs, but maybe someone here knows the right trick?
>
> If not, does anyone know glibc well enough to tell me if it is
> possible to rip the right pieces from it and create a "math" module
> from them?
>
Hmmpf. I encountered a similar task in the IP-Noise project when I needed
a log in the kernel. I eventually managed to:
1. Rip the i386's log implementation from glibc and use it for i386
modules. It was very hard.
2. Write a portable implementation of log in C, and then compile it for
every architecture. However, I discovered that running FPU code in the
SPARC kernel was not allowed. It may be of use on other architectures.
You can find the code in the IP-Noise CVS. Send me a private E-mail for
the exact URL.
I read somewhere that kernel modules are not supposed to use FPU code,
because the registers are not protected when switching from user-land to
kernel-land. So far it did not disturb us, but it is an issue one should
be aware of.
Regards,
Shlomi Fish
> --
> Oleg Goldshmidt | [EMAIL PROTECTED]
> [Lisp] is the only computer language that is beautiful.
> - Neal Stephenson
>
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Shlomi Fish [EMAIL PROTECTED]
Home Page: http://t2.technion.ac.il/~shlomif/
Home E-mail: [EMAIL PROTECTED]
"Let's suppose you have a table with 2^n cups..."
"Wait a second - is n a natural number?"
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