Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!romp!auschs!reed!d75!ireland!jon From: jon@ireland.uucp (Jon Doran) Newsgroups: comp.sys.m68k Subject: Re: using shared memory to talk to physical memory on a Motorala 147 Summary: Left off an undocumented argument to shmat Keywords: Short I/O, Shared Memory, MVME147, M68030 Message-ID: <2866@d75.UUCP> Date: 11 Dec 89 19:06:43 GMT References: Sender: news@d75.UUCP Reply-To: jon@ireland.austin.ibm.com.UUCP (Jon Doran) Distribution: comp.sys.m68k Organization: IBM AWD, Austin, TX Lines: 20 Yeh, ran into this before... There is a fourth argument to the shmat library routine, it isn't mentioned in the bound documentation, but you should be able to find it online. If memory serves me correctly it should be the physical address to attach to. Which brings up another, more serious, problem. Once you can stomp all over physical memory, one is naturally tempted to bash on attached VME cards. There are all sorts of control registers you can access, in a multi-processor environment you can reboot an attached processor by altering its control register, you can modify disk controller registers, etc. These registers are in a region of the bus address space known as short I/O. And the only way I know of to get to them is to write your own device driver. Should be the shortest driver ever written... Sorry I don't have one to post, I don't work on Motorola boards these days. Perhaps someone could put one together? Jon