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SubjectRe: Userland Kernel Download Tool
DG,

you already have complete dependency information in the kernel source,
otherwise the config system wouldn't work. unfortunately, this requires
active parsing of the source tree, but i imagine we could cache the data
we extract and generally make it tolerably efficient.

who's up to writing a pre-processor in perl? ;^)

of course, we still have the Development Model to think about here...
we're a rather haggard, unorganized, decentralized lot of rogues. this is
why our kernel (and the rest of our OS) is Better Than Theirs Is. making a
partial-download-available thing is a neat idea, but how do we distribute
it and who do we trust with our on-the-fly modified source tree? any
checksum verification is right out the window.

so, i'll not stand in your way (i like the idea, everyone that deals with
newbies likes the idea of "make it simple for the newbies", but it's got
definite issues).

why do i think i'm going to get flamed for contributing to a rehash of
this thread??...
--
/jbm, but you can call me Josh. Really, you can.
"Lightsabres aren't Open Source!"
-- esr in User Friendly

Verily, thus sayeth dg50@daimlerchrysler.com upon Thu, 13 Jan 2000:

> Hello everyone,
>
> There's quite a bit of pie-in-the-sky here, but I've had an idea that I'd
> like to share.
>
> Sitting on my /usr/src partition is a great big whalloping hunk of data -
> the Linux kernel sources. Of that data, only a very small part of it is
> actually used in the production of the kernel for my machine. Most of that
> space is wasted.
>
> Not only that, but as I had to get that data across the network, a great
> whalloping bunch of bandwidth was wasted too, and is continually wasted
> each time the kernel is updated. Downloading changes as patches instead of
> the whole tree helps some, but it is entirely possible that a given upgrade
> - say, 2.2.13 to 2.2.14 - might update files that are never actually used
> by me. It's possible - not likely, but possible - that the only thing that
> really happened during MY kernel upgrade was that the kernel version number
> got bumped.
>
> Now take all that wasted storage space and wasted bandwidth, and multiply
> it by World Domination and an increasing number of supported platforms. I
> think that Linux on IBM Big Iron is wonderful - but I don't want to
> download it and keep it on my P233. ;)
>
> This is certainly not a new idea - every once and a while, someone will
> suggest Linux be spit up by arch, or by drivers, or by whatever - and then
> Linus and a few others will re-state the problems associated with revision
> control etc. splitting up the sources would cause, and the idea dies (or
> perhaps "is assassinated" :)
>
> I agree completely here. Developing the Kernel should be kept as easy and
> as straightforward as possible. Anything that interferes with this design
> goal (as even things like CVS would) is tampering with success and is
> probably a bad idea.
>
> So anything that is designed to streamline what a user must download
> ("user" in this case representing a kernel non-developer) must have
> near-zero impact on the existing development process. It must be invisible
> and transparent.
>
> Here's the idea I have: create a user-space, server-based tool with a
> simple API and protocol that sits on top of an uncompressed kernel source
> tree. This server-based tool is talked to by a client (it could be a CGI
> program, or a desktop program, or a Java applet or whatever) that presents
> a little menu to the user. The user makes a few selections that reflect at
> a high level what hardware he has, and the server tool builds a little
> custom tarball that contains just the sources needed to compile a kernel
> for that user. Ideally, it should also touch the "make fooconfig" files
> just enough so that options that require sources that are not provided in
> the custom tarball are greyed out or not selectable.
>
> Even better would be an option where the user specifies what current
> sources he has, and what is generated is a tarball of the sources that have
> changed since his last download - and even better yet, _patches_ to sources
> he already has.
>
> This need not be an all-singing, all dancing tool right from the get-go
> either. In fact, I think a first kick at this cat might have only one user
> option - arch. That alone would reduce download sizes and required storage
> by a factor of however many main arches there are right now - 6? 7?. Later
> versions could be kept general: "I have a SCSI card" "I have a network
> card" "I want sound support" as opposed to "I have an Adaptec Model
> 8000-K1WqA".
>
> What I worry about though is the meta-data that the program would need to
> keep; specifically, the maintainence of it. If the source file
> "ataptec_8000-K1WqA.c" belongs in the "SCSI card" option tarball, then
> something needs to tie that dependancy together - and creating that
> dependancy should not rely on someone (like the developer) explicitly
> defining it - because if it does, then there will be developers who either
> won't do it or will forget to do it or won't know that they are expected to
> do it - and then the process falls apart.
>
> Ideally, the meta-data should be implicit in the kernel source tree. If I
> want everything in for intel x86, then I grab linux/arch/x86. If I don't
> want SCSI, then I don't grab linux/arch/x86/drivers/devices/SCSI etc.
>
> However, I worry that the current src tree may not be organized that
> rigidly, that there may be cross-directory dependancies that cannot be
> inferred from a given source code file's position in the filesystem. If
> that is the case, then either the program must be made aware of these
> dependancies (which means kernel devlopers maintaining them - not good) or
> the current source tree must be reorganized so that files in lower
> directories only depend on files higher up in their filesystem tree (so
> linux/arch/x86/drivers/devices/SCSI/adaptec/ataptec_8000-K1WqA.c may depend
> on linux/arch/x86/drivers/devices/SCSI/scsi.c but not
> linux/arch/x86/drivers/devices/IDE/disks.c)
>
> I think that the "right way to do it" is to re-org (if necessary) the src
> filesystem, as it has benefits other than just enabling a nifty user space
> utillity. However, this may be a lot of work for what may be very little
> visible gain. If, for example, the choice for 2.4 was to either re-org the
> file tree or to get a fully robust, high-speed NFS implementation working,
> it's hard to argue against choosing fixing NFS over re-orging the source
> tree, even if I don't use it myself. :(
>
> Comments?
>
> DG
>
>
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