I'm investigating the feasibility of an user space pseudo device driver
realized in this way:
HOW:
- a kernel module that register a set of char devices and install a
fully defined file_operations
- associated with this set there is another character device
- polling and reading from this device a daemon get the identification
info and the file_operations callback arguments (of course other
callbacks are needed, by example a munmap callback)
- when ready the daemon will write the answer back
- the kernel module never pass to daemon the data pointed by user space
pointer argument of syscalls but it pass the pointer. The daemon will
read/write the data directly from process user space (I assume using
/proc/PID/mem)
WHY:
- to realize compatibility layer
- to emulate inexistant devices
- to test a device driver in a MMU controlled environment
- to reduce kernel bloat moving more code to user space (?)
- ...
PROBLEMS:
- I've tought to mmap /proc/PID/mem but I see that in 2.2 this was
deprecated and in 2.3 this chance does not exists (comparing 2.2 and 2.3
I suppose that this has happened during Al rewrite of fs/proc/base.c).
Does it exists some alternatives? This opportunity will never reappear?
I'd like to hear all your comments and consideration.
-- Abramo Bagnara mailto:abramo@alsa-project.orgOpera Unica Via Emilia Interna, 140 Phone: +39.0546.656023 48014 Castel Bolognese (RA) - Italy Fax: +39.0546.656023
ALSA project is http://www.alsa-project.org sponsored by SuSE Linux http://www.suse.com
It sounds good!
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This archive was generated by hypermail 2b29 : Wed Apr 19 2000 - 12:43:37 EDT