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Re: CVS commit: src/sys/arch

On Sat, Jul 24, 2010 at 04:49:28PM +0200, Matthias Drochner wrote:
> said:
> > How about making paddr_t always 64bit? That makes it much easier to
> > deal with in libkvm.
> I don't think this is a good argument. The little gain of making
> a rarely used library like libkvm simpler can't justify adding
> overhead to the kernel.

libkvm is hardly an issue.  Kernel modules, on the other hand...

> PAE is a "bridge technology", interesting only for few systems.
> Users of low-end i386 systems would be penalized, and most users
> of boxes with >4G memory would gain nothing because they run
> a 64-bit system anyway.
> So, imho, no kernel overhead is acceptable.

Well, that's one opinion.  My own, probably just as humble, is that such
a gaping ABI incompatibility is completely unacceptable, especially
after all the work that has been done to make some kernel subsystems a
little bit more responsible regarding ABI.

I'm really curious to see some actual measurements about that alleged
overhead.  The way I see it right now, we have a known lethal ABI
incompatibility versus an alleged overhead of unknown size.

Quentin Garnier - -
"See the look on my face from staying too long in one place
[...] every time the morning breaks I know I'm closer to falling"
KT Tunstall, Saving My Face, Drastic Fantastic, 2007.

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