Linked by Thom Holwerda on Tue 18th Jul 2006 22:51 UTC, submitted by Raffaele
Amiga & AROS "In a previous item, we described how the AmigaOS4.0 memory system works in terms of managing memory allocations from the top. However, there is more to allocating memory than that. The object caches of course work on memory that has already been mapped into the virtual memory space. But both the virtual address ranges, as well as the physical memory has to come from a source, too."
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See, and that is not (entirely) true. While it is true for existing applications, the new kernel takes precautions already towards that goal. It will not work immediately because it simply would break all existing code.

However, AmigaOS4 marks executeable memory as "read only", which simply does not allow a broken application to trash code in the system. While this is not real memory protection, it is certainly a step into a more robust system.

Also, crahses are now cought thru a system level debugger, the "GrimReaper", which, in case you have an SDK installed, lets you attach the crashed app to gdb and debug it there.

Further more, the new exec kernel provides already APIs in respect for future memory protection (and SMP support). e.g. AllocSysObject() is a new way of allocating system resources instead of using malloc( struct foo); You can expect applications written with this in mind to work fine if/when mem protection (and resource tracking) will become available.

More then that, the whole process/task modell has been revamped to support threads now (child tasks) as well as this handling is now mature (while I would consider this broken in anything other version before 4).

While going ppc might look like a mistake in the first place, it is also clear, going x86 would position the OS in direct competition to other OSs on that said platform. I think, OS4 can even function as a rebirth of the ppc. Thru it's license scheme it allows clone builders to build open hardware, and thus would encourage competition. However, we are in a chicken-and-egg situation, but even that problem got solved sometimes back in the past by someone ;)

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