Re: [PATCH prototype] [0/8] Predictive bitmaps for ELF executables

Andrew Morton
2008-03-19T19:29:12Z

On Tue, 18 Mar 2008 18:20:45 +0100 Andi Kleen <andi@firstfloor.org> wrote:

> > What's the permission problem? executable-but-not-readable files? Could
>
> Not writable.

Oh.

I doubt if a userspace implementation would even try to alter the ELF
files, really - there seems to be no point in it. This is just complexity
which was added by trying to do it in the kernel.

> > be handled by passing your request to a suitable-privileged server process,
> > I guess.
>
> Yes it could, but i dont even want to thi nk about all the issues of
> doing such an interface. It is basically an microkernelish approach.
> I prefer monolithic simplicity.

It's not complex at all. Pass a null-terminated pathname to the server and
keep running. The server will asynchronously read your pages for you.

That's assuming executable+unreadable libraries and binaries actually need
to be handled. If not: no server needed.

> e.g. i am pretty sure your user space implementation would be far
> more complicated than a nicely streamlined kernel implementation.
> And I am really not a friend of unnecessary complexity. In the end
> complexity hurts you, no matter if it is in ring 3 or ring 0.

There is no complexity here.