Date: Mon, 13 Sep 2004 23:18:00 -0700
From: William Lee Irwin III <wli@holomorphy.com>
To: Roger Luethi <rl@hellgate.ch>
Cc: Albert Cahalan <albert@users.sf.net>, Andrew Morton OSDL <akpm@osdl.org>,
       linux-kernel mailing list <linux-kernel@vger.kernel.org>,
       Paul Jackson <pj@sgi.com>
Subject: Re: [1/1][PATCH] nproc v2: netlink access to /proc information
Message-ID: <20040914061800.GD9106@holomorphy.com>
References: <20040908184028.GA10840@k3.hellgate.ch> <20040908184130.GA12691@k3.hellgate.ch> <20040909003529.GI3106@holomorphy.com> <20040909184300.GA28278@k3.hellgate.ch> <20040909184933.GG3106@holomorphy.com> <20040909191142.GA30151@k3.hellgate.ch> <1094941556.1173.12.camel@cube> <20040914055946.GA20929@k3.hellgate.ch>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20040914055946.GA20929@k3.hellgate.ch>
Organization: The Domain of Holomorphy
User-Agent: Mutt/1.5.6+20040722i
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 2424
Lines: 47

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.


-- wli
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/