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Re: [Qemu-discuss] Coldfire 5282 Support

From: William Mahoney
Subject: Re: [Qemu-discuss] Coldfire 5282 Support
Date: Tue, 24 Oct 2017 20:34:55 +0000

Quick question. On the MCF5282 there is a huge memory mapped IO starting at 
0x40000000 and going for 1A0000. All of the IO is relative to this starting 
point, so when my call back for an I/O write happens, for example, I get the 
offset into the area. Fine.

In this area is the Fast Ethernet Controller (FEC) at offset 1000. The support 
for the FEC is already done in the hardware for 68K in general, so that’s 
great, only the address is different. Easily solved. But… It essentially 
creates a “hole” in the region at location 1000. The same is true of the 
timers, since that was done for the 5208. 

1) If I define the large region and THEN define the small one (since FEC 
support is already done), will the “more recent” region get the I/O requests 
and I’m good to go? And if so, will my “below the FEC” part and the “above the 
FEC” part still have the correct offsets?

2) If that is not the case, I define “the below the FEC” part in one IO space, 
the “above the FEC in another IO space, and then adjust the offsets for “above” 

Or a different way of saying this is “Is there any priority for overlapping 
defined I/O spaces, and if so is it LIFO?”



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