Re: Is it possible to read a SGA's memory architecture ?

Norman Dunbar wrote:

> Morning Billy, or is it evening is SA ?

GMT+2. Close too British time. :-)

> As far as I know, Precise only runs a
> client on Windows, having some 'agent' or something running on the
> server (Unix) doing the attaching and detaching to/from the SGA -
> however it does it.

I find this level of hacking by commercial software vendors fascinating. One of the most incredible feats IMO was from IBM.

After Microsoft grabbed its toys and walked out of the OS/2 project, IBM still had (under their contract), access to Windows source code. However, with WFW3.11, a lot changed at kernel level in Windows. IBM was however still able to provide 'native' support for Win16 apps in OS/2 2.0.

Doing some low level debugging showed why. The IBM developers loaded the Windows kernel and performed in memory patching of the kernel, installing OS/2 kernel hooks. Thus the app could run natively in a Win16 VM inside OS/2.

The only way they could do it, was to reverse engineer the binary Win16 kernel. Which of course was illegal according to the Microsoft licensing for Windows. Having the original kernel source must have helped too.

At the time there was speculation that Microsoft in fact had a legal case against IBM and could take them to court. Never happened though. Think that Microsoft did not like the idea of battling IBM in a court of law.

BTW, Microsoft did the reverse with IBM. As they had OS/2 kernel source, they added native OS/2 support into NT. Only for console apps though. Even so, it was excellent.

We failed trying to do a Gupta db re-org on OS/2. We tried a bigger machine and without success. OS/2 and Gupta kept on crashing after 10+ hours runtime.

Eventually out of desperation, we used NT. I was playing around with the OS/2 subsystem on NT at the time and we thought we give it a bash. 3 hours later, the Gupta re-org was completed.

> I'm not into system programming much (on Windows or
> Unix) so I don't really know.

That's something that I like even more at times then mucking about in Oracle. :-)

--
Billy