Messages in this thread | | | Date | Wed, 14 Jan 2009 11:18:28 +0100 | From | Philippe De Muyter <> | Subject | Re: linux kernel without file system |
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On Wed, Jan 14, 2009 at 10:52:24AM +0100, Xavier Bestel wrote: > > On Wed, 2009-01-14 at 10:34 +0100, Philippe De Muyter wrote: > > On Wed, Jan 14, 2009 at 09:46:48AM +0100, Tomasz Chmielewski wrote: > > >> I need to design a very small embedded system that must only control > > >> one ethernet port and two serial lines and must fit in a very small flash > > >> memory. So I thought about replacing the call to /etc/init by my > > >> application > > >> program and removing all the file-system part of linux. > > >> Is that doable ? > > >> Is there a 'standard' way of doing that ? > > >> The first problem I see is accessing my serial lines. How could I do that > > >> without using open("/dev/ttySx"), which requires a file system ? > > >> Is there a way to access devices that does not require a file-system ? > > > > > > You could put everything in initramfs (and embed it in the kernel). > > > > Actually, I was thinking about reducing the footprint of my kernel by > > removing all the fs-related system calls, so the problem is not where > > the file-system is, but how to access (serial) devices without giving their > > "/dev/..." name. > > You can still mount sysfs somewhere and access the device nodes from > there.
Keeping thinking about it, I now think that my 'application program' (basically a serial-to-ethernet converter) should be a kernel thread, because of the small memory constraints.
The question is thus how to access the serial lines from a kernel thread.
Philippe
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