Subject: Re: Revision K strongarms ...
To: None <kim@pvv.ntnu.no>
From: Oli <ssu97opc@reading.ac.uk>
List: port-arm32
Date: 05/07/1998 15:08:56
On Thu, 7 May 1998 kim@pvv.ntnu.no wrote:
> > If you mean `modify the linker so it _does_ page align everything', that would
> > cause tremendous code bloat. For example, the GNU C library contains 1076
> > object files. Assuming that, on average, you'd waste half a page per object
> > by aligning them, that would cost you a total of over 2MB. In fact it's even
> > worse than that because a significant number of them are much smaller than a
> > single page - they only contain a few hundred bytes of code. So again, it's
> > possible, but you have to weigh up whether it's actually worth the cost. If
> > you _did_ do this, you would either have to maintain two versions of
> > everything, or foist this wastage of space onto everybody who uses NetBSD, the
> > majority of whom probably don't have CPUs with this problem.
>
> Then don't page align the code. Just let the linker put a NOP at the
> end of each page.
>
> This of course puts NOPs in the middle of the code, but the linker should
> be able to handle that, since it must contain references to branches
> and indexes. I don't know how this apply to PIC code though.
>
> Km0
>
Erm, the linker doesn't page align, so it cant put a nop at the end of the
page. If the extra nops are in the middle of the pages, then it doesn't
stop STM^ ' s from ending up on page boundries.
Oli
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