Messages in this thread | | | Subject | Re: [PATCH] Open Firmware device tree virtual filesystem | From | Benjamin Herrenschmidt <> | Date | Tue, 02 Jan 2007 15:57:05 +1100 |
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> I think there is high value in an OFW filesystem representation > that gives you _EXACTLY_ what the OFW command line prompt does > when you try to traverse the device tree from there, and that > is what openpromfs tries to do.
Except that every OFW implementation I have here shows you different things for the same original binary data :-)
> If you want raw access, use a character device or a similar auxilliary > access to the data items. Another idea is to provide a seperate file > operation (such as ioctl) on the OFW property files in order to fetch > things raw and in binary. > > When I get some binary data out of a procfs or sysfs file I feel like > strangling somebody. I'm grovelling around in a filesystem from the > command line so that I can get some information as a user. If you > don't give me text I can't tell what the heck it is. > > Simple system tools should not need to interpret binary data in > order to provide access to simple structured data like this, that's > just stupid.
I would agree with you if the data was properly typed in the first place but it's not, thus you end up with heuristics and I hate heuristics in the kernel :-) Now, that's also why everybody on ppc has "lsprop" at hand which does the "pretty printing" thing.
I like being able to have a simple way (ie. tar /proc/device-tree) to tell user to send me their DT and have in the end an exact binary representation so I can actually dig for problems, like a wrong phandle in an interrupt-map or stuff like that...
Cheers, Ben.
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