Messages in this thread | | | Date | Mon, 13 Sep 2004 23:18:00 -0700 | From | William Lee Irwin III <> | Subject | Re: [1/1][PATCH] nproc v2: netlink access to /proc information |
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On Sat, 11 Sep 2004 18:25:56 -0400, Albert Cahalan wrote: >> No. First of all, I think they can be offered. Until proven >> otherwise, I'll assume that the !CONFIG_MMU case is buggy.
On Tue, Sep 14, 2004 at 07:59:46AM +0200, Roger Luethi wrote: > I agree with you that those specific fields should be offered for > !CONFIG_MMU. However, if for some reason they cannot carry a value > that fits the field description, they should not be offered at all. The > ambiguity of having 0 mean either "0" or "this field is not available" > is bad. Trying to read a specific field _can_ fail, and applications > had better handle that case (it's still trivial compared to having to > parse different /proc file layouts depending on the configuration).
Apart from doing something it's supposed to for !CONFIG_MMU and using the internal kernel accounting I set up for the CONFIG_MMU=y case I'm not very concerned about this. I have a vague notion there should probably be some consistency with the /proc/ precedent but am not particularly tied to it. We should probably ask Greg Ungerer (the maintainer of the external MMU-less patches) about what he prefers since it's likely we can't anticipate all of the !CONFIG_MMU concerns.
On Sat, 11 Sep 2004 18:25:56 -0400, Albert Cahalan wrote: >> mean that fewer apps can run on !CONFIG_MMU boxes. It's >> same problem as "All the world's a VAX". It's better that >> the apps work; an author working on a Pentium 4 Xeon is >> likely to write code that relies on the fields and might >> not really understand what "no MMU" is all about.
On Tue, Sep 14, 2004 at 07:59:46AM +0200, Roger Luethi wrote: > The presumed wrong assumptions underlying broken tools of the future > are not a good base for designing a new interface. My interest is in > making it easy to write correct applications (or in fixing broken apps > that won't work, say, on !CONFIG_MMU systems).
I don't really know what the approach to app compatibility used by userspace for !CONFIG_MMU is; I'll refer you to Greg Ungerer as my knowledge of the CONFIG_MMU usage models and/or whatever userspace is used in tandem with it outside the VM's internals is rather scant.
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