Linked by Thom Holwerda on Mon 17th Oct 2011 20:59 UTC, submitted by Ola Jensen
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RE[7]: No memory protection
by Alfman on Wed 19th Oct 2011 10:04
in reply to "RE[6]: No memory protection"
viton,
"AmigaOS is a Single Address Space OS, where an App or OS can pick any object of other applications. That makes data passing and sharing easy and fast."
Oh I see, thanks for the answer So it's about shared objects... Well I guess at least it's a good technical reason for not having protection.
RE[8]: No memory protection
by madcrow on Wed 19th Oct 2011 23:00
in reply to "RE[7]: No memory protection"
RE[7]: No memory protection
by tylerdurden on Wed 19th Oct 2011 19:08
in reply to "RE[6]: No memory protection"
You can still emulate a single address space, with memory protection.
I can understand that adds some complexity to the OS design. But then the problem is then code complexity, not performance overhead from memory protection (which is practically a non-issue in most modern architectures).
But then it is not my project. So whatever it is they want to do, it is their pregogative.
Edited 2011-10-19 19:11 UTC
RE[8]: No memory protection
by ncafferkey on Thu 20th Oct 2011 02:26
in reply to "RE[7]: No memory protection"
RE[8]: No memory protection
by viton on Thu 20th Oct 2011 13:45
in reply to "RE[7]: No memory protection"
You can still emulate a single address space, with memory protection.
So this is what I meant. You need to set access attributes to memory allocations (pages) in a hierarchical way to keep controlled access of different layers of OS to your exposed data. If data is not exposed, it is solely belongs to an app.
Also, page size is 4KB min, so memory blocks (like messages, taglists, IO requests, shared data) need to be sorted and merged by their access rights.
Almost no chance of getting this without software modification.
Edited 2011-10-20 13:48 UTC




Member since:
2005-08-09
AmigaOS is a Single Address Space OS, where an App or OS can pick any object of other applications. That makes data passing and sharing easy and fast. As I see it, the only way to do memory protection transparently is protection domains that require tagged memory allocations to specify data access rights.