Re: Tagged memory (was Re: Memory Upgrade) -- MIDRANGE-L

This hardware/software discussion made me think.
Ultimately, whatever hardware does on computer, it is sofware that is
responsible for what hardware is doing.
Software in a way is the soft spot of any system (pun intended).

Whatever hardware protection exists, you can always track it back to the
point where software sets up hardware mode of operation. If at this point
you can change/patch software, you can bypass or cheat hardware.
For example - hardware uses page tables to protect sensitive areas from
unauthorized access.
However, page tables are set up by software, so if you patch a piece of
code which sets up page tables, no hardware will be able to do anything
with this.

>From this point of view - no computer system in the world is immune -
except some embedded systems where "software" is hardwired in memory. There
were also some systems in the past, which had separate CPUs and separate
memories for application code and for system code, which prevented
application code to access system storage (System 36 was designed that
way). However, even that system could be patched.

On some systems you do not even have to patch - take Linux, for example.
You do not need to guess the meaning of the code looking at cryptic
disassembler listings and then to do patching struggling with cumbersome
hex codes etc. You have full access to source code with all comments - just
change source, recompile, replace the module and that's it.
Provided, of course, you are authorized to do these changes to the system.

Bottom line  - be careful about who is authorized to what on your system -
whatever platform you have. A person with enough authority can do amazing
things to a system.

    Alexei Pytel





                    "Leif Svalgaard"
                    <leif@attglobal.net       To:     <midrange-l@midrange.com>
                    >                         cc:
                    Sent by:                  Subject:     Re: Tagged memory 
(was Re: Memory
                    midrange-l-admin@mi        Upgrade)
                    drange.com


                    09/29/2001 05:37 PM
                    Please respond to
                    midrange-l





From: Alexei Pytel <pytel@us.ibm.com>
> Excuse me my stupidity, but I really do not see the point ???
> Of course, if instructions to do this are lying around and you can do the
> patching work without authority, then it's trouble ...

This is precisely what some people know how to do on the AS/400.
This list is not the place to discuss this. But to deny it is just sticking
your head in the sand.

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