[cdt-dev] RE: CDT/GDB issue

["Derek Morris" <dmsubs@xxxxxxxxxxxxx>]

I've just thought about this and realised that Eclipse is not doing the
wrong thing. The problem must lie with my GDB or target system returning
invalid for the whole memory block...

I'll investigate.

> -----Original Message-----
> From: Derek Morris [mailto:dmsubs@xxxxxxxxxxxxx] 
> Sent: 06 May 2006 08:41
> To: 'cdt-dev@xxxxxxxxxxx'
> Subject: CDT/GDB issue
> 
> Hi,
> 
> I am using Eclipse to debug an embedded system. The embedded 
> system has a sparse memory map. That is, it is not a 
> contiguous space. If I try to access non-existant memory, I 
> get memory faults.
> 
> I have a valid memory space that starts at 0xff000000. In the 
> Eclipse memory viewer, if I try to display this address, each 
> memory location is displayed as "??????". If I do this in 
> GDB, it reads correctly.
> 
> Looking at the MI debug trace:
> 
> [1,146,900,580,732] 68-data-read-memory 4278189760 x 1 1 976 
> [1,146,900,580,752] 
> 68^done,addr="0xfefffec0",nr-bytes="0",total-bytes="976",next-
> row="0xff000290",p\
> rev-row="0xfefffaf0",next-page="0xff000290",prev-page="0xfefff
> af0",memory=[{addr="0xfefffec0",data=[\
> "N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N
> /A","N/A","N/A","N/A","N/A","N/A","N/A\
> ","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A",
> "N/A","N/A","N/A","N/A","N/A","N/A","N\
> /A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A
> ","N/A","N/A","N/A","N/A","N/A","N/A",\
> "N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N
> /A","N/A","N/A","N/A","N/A","N/A","N/A\
> ","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A","N/A",
> "N/A","N/A","N/A",
> Etc
> 
> It is reading memory from 0xfefffec0 (4278189760), which in 
> my system is invalid. I assume this is to cache the memory 
> before (and after) the data I want. GDB seems to be returning 
> invalid data for the whole requested block (inlcuding the 
> valid memory).
> 
> Can I stop Eclipse doing this (requesting memory before the 
> adsress I want)? Is GDB at fault for returning invalid data 
> over the whole block?
> 
> Any help/advise/pointers gratefully received.
> 
> ---
> Derek