RomRaider

In this topic:
viewtopic.php?f=40&t=6303
Why is the RAM size increased?

Anyone know?

I'm not sure. I don't see a reason for it as anything past the RAMs actual size will not be valid to read and write.

It makes no sense too me but I thought perhaps it was for some virtual RAM or something.

The processor peripheral addresses occupy this extra space (ports, CAN, ATU, etc).

The peripherals do occupy RAM address space, just not in the extra range suggested to be added to the default RAM size. Please refer to the CPU Summary spreadsheet in the post viewtopic.php?p=56752#p56752 for the correct peripheral address range. This space is usually defined when you select the CPU type in IDA if you have the extra CFG data defined in the IDA sh3 file (same post).

Actually they do occupy that range, at least for SH7058.. I can't speak to SH7055. SH7058 peripherals are something like 0xFFFFD000 - 0xFFFFF87F. That's why you set the upper limit to 0xFFFFFFFF not 0xFFFFBFFF.

I'll have to mess with with the CFG some more. IDA automatically defines names for everything in the CFG, but it doesn't automatically create a segment for the peripherals. This is on IDA 6.9.151221 (32-bit) The only way I have been able to get the names in the CFG to populate is to set RAM upper limit to 0xFFFFFFFE before the initial analysis.

Also, if you have issues setting RAM length to 0xFFFF, where the segment is only 1 byte, try setting length to 0xFFFE.

You are correct, my hex math failed me in the last post. With the correct sh3 CFG file there is no reason to extend the RAM range though. IDA will define the peripherals and assign the correct address and decode the instructions directly related to them.