Fundamental defect of the concept of shared libraries

Masataka Ohta mohta at necom830.cc.titech.ac.jp
Mon May 20 20:08:45 AEST 1991


In article <MWM.91May17132439 at raven.pa.dec.com>
	mwm at pa.dec.com (Mike (My Watch Has Windows) Meyer) writes:

>   Even worse, with some architechture, it is impossible to map several virtual
>   addresses to a physical address. Virtually tagged cache and inverted
>   page tables are notable examples.

>So some architechtures can't support shared libraries? Well, don't put
>shared libraries on them.

That's what I am saying.

>Some architechtures can't support demand
>paged memory, or virtual address spaces, or preemptive scheduling.
>Does that mean we have to live without them on machines that can
>support them?  No; it doesn't.

You don't know about hardware enough. Because address translation is time
consuming, fast cache is always indexed by virtual address. Thesedays,
virtually indexed cache is quite common.

So, if you want shared libraries, you can put it only on slower machines.

>No, I understand that you aren't qualified to do systems design work.

You understand nothing.

As you don't know enough about hardware, you aren't qualified to do
systems design work.

						Masataka Ohta



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