[maemo-developers] [maemo-developers] XIP, CELinux collaboration

[From: Nils Faerber]

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Gustavo Sverzut Barbieri schrieb:
> Hello,
Hi!

> 1) Why not use eXecute In Place?

I guess it will be way too slow on a complex device like the 770.
XIP would require that code is paged in from the quite slow flash
device. This would additionally decrease performance since the NAND
flash is a lot slower than the SDRAM.
For normal operation the Linux kernel helps us a lot with its caching,
i.e. if we still have plenty of memory free then the used pages will end
up in RAM and are fast to access.
If memory runs tight only the active pages reside in RAM the rest will
be paged into RAM on usage - a little slower than directly XIP them but
for normal use I guess we get a lot more performance out of it than we
loose memory. It is a trade off of course, but with 64MB RAM the choice
is IMHO correct not to use XIP.
If we just had 32MB or even less then XIP might be a nice option. But
then again the system would have to be simplified too. Having ~20 to 30
depending libraries per executable would not be very clever then ;)

> 2) There is any collaboration with http://tree.celinuxforum.org/CelfPubWiki ?

At least not to my knowledge but the Nokia core team should better
comment on this!

> Gustavo Sverzut Barbieri
Cheers
  nils faerber

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