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| Poster | Thread |  NutsAboutAmiga
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Memory protection, the theoretical difference between operating systems.
Posted on 20-Mar-2015 15:02:22
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Elite Member
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Joined: 9-Jun-2004
Posts: 12818
From: Norway | | |
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| @ne_one
Quote:
@NutsAboutAmiga
There are so many areas that need to be addressed that the scale clearly tips in favour of adding what is missing from the Amiga onto something else.
Like perhaps something that could be seen as the modern, spiritual successor to AmigaOS...?
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As I understand it, the basic principles around Amiga is different way things works in Linux, in Linux you do a interrupt to jump into the kernel, this forces an exclusive access to kernel, you can get kernel panic; this is because while you have memory protection. Everything inside the kernel is in the same memory space, so if a driver crashes it, can bring down the kernel, because its part of it.
Similar the way programs work, when program starts it link's itself with all the .so objects, so ELF .data space is with same memory, making the memory of .so object exclusive to the program, so if the program crashes, it only brings down itself.
On Amiga on the other hand, program code is considered read only, and is available to all programs, ELF .data might be shared or not, depending on the "const" flag, everything else is shared unless specified not to be, using the MEMF_Private flag.
AmigaOS4.1 does support .SO objects in AmigaOS4, but instead of sharing code and making the .data private, everything it's linked into the .EXE file.
Is it possible, well it’s a lot of work, you need to make the kernel exclusive, or maybe move some of the stuff into .so files.
All public lists, like screens, windows etc, need to be accessed differently, so porting a program from Amiga OS to Next OS, you most do some heavy rewrite, no more obj->item or obj.item, for things that can't be shared.
Last edited by NutsAboutAmiga on 20-Mar-2015 at 03:23 PM.
Last edited by NutsAboutAmiga on 20-Mar-2015 at 03:06 PM.
Last edited by NutsAboutAmiga on 20-Mar-2015 at 03:03 PM.
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| | Massi
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Re: Memory protection, the theoretical difference between operating systems.
Posted on 23-Mar-2015 14:36:11
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Cult Member
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Joined: 2-Feb-2011
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From: Rome, Italy | | |
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| @NutsAboutAmiga
Sorry it feels like I missed something.
Is this thread supposed to analyse memory protection on the various operating systems?
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