Re: [RFC] Wine speedup through kernel module

From: Tigran Aivazian (tigran@veritas.com)
Date: Thu Sep 07 2000 - 04:22:32 EST


Hi David,

> I'm also interested in finding a better way of getting to kernel space from
> user space... Currently, this involves the client process opening a proc file
> and doing ioctl's on it to request Win32 operations (easy to do from a kernel
> module).

how about the classical standard way of "getting to kernel space", i.e.
plain system calls? Unless you really need a huge number of new system
calls, what you can do is in the module, scan for sys_ni_syscall entries
in the sys_call_table[] table (see entry.S) and replace them with pointers
to functions in your module's address space. Then you need to communicate
the slot numbers thus occupied back to userspace, e.g. via /proc file
which then can invoke them in a standard int 0x80 manner. Or you can
hardcode the slots but that is not flexible because unoccupied slots may
become occupied at any time in the future.

Also, if you do this - don't forget to inc/dec module refcount in each of
your new syscalls, for obvious reasons - if the syscall sleeps and the
module is unloaded, it will return to "nowhere".

Regards,
Tigran

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