Re: [platform-debug-dev] Memory view reads before base address

[Stefan Bylund <steby@xxxxxxx>]

Hi,

We have two use cases for the Memory view. Either via a GDB debugging 
session in CDT or via a custom view where you can look at memory for a 
selected process. For the first case, GDB helps us and fills in "not 
available" bytes for incomplete memory blocks. For the other case, I 
missed that you can use the two methods below, I just returned null as 
is done in CDT's memory block implementation and in an example memory 
block implementation I found in a presentation from Samantha. I will try 
to use those methods for our custom case and hopefully that will solve 
our problem.

Regards,
/Stefan


Samantha Chan wrote:

> IMemoryBlockExtension already has APIs that allow clients to specify the
> start and end address of the memory block.
>
> Look at the following APIs in IMemoryBlockExtension:
> - public BigInteger getMemoryBlockStartAddress() throws DebugException;
> - public BigInteger getMemoryBlockEndAddress() throws DebugException;
>
> The table renderings should not ask for memory beyond the range as
> specified by the start and end address.
>
> In addition, Mikhail is right, the model/engine can also control how it
> retrieves memory from the engine.  The draw back of this is that the user
> can still scroll beyond the range supported by the backend and will end up
> just getting dummy data populated in the Memory View.
>
> Thanks...
> Samantha
>
>
>
>                                                                           
>             "Mikhail                                                      
>             Khodjaiants"                                                  
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>                                       RE: [platform-debug-dev] Memory     
>             13/12/2007 06:21          view reads before base address      
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>
>
> Hi Stefan,
>
> As far as I understand the Memory view just requests a range of memory.
> If the requested memory or part of it is not readable it is up to the
> backend to decide to retrieve it or not. Not sure that adding a special
> option for it is a good idea.
>
> Mikhail Khodjaiants
>
> -----Original Message-----
> From: platform-debug-dev-bounces@xxxxxxxxxxx
> [mailto:platform-debug-dev-bounces@xxxxxxxxxxx] On Behalf Of subs
> Sent: 13 December 2007 10:00
> To: Eclipse Platform Debug component developers list.
> Subject: Re: [platform-debug-dev] Memory view reads before base address
>
> Stefan,
>
> This is a good idea, and I'd like to add a couple of additional
> requests:
> - You should be able to specify the base/size or start/end address of a
> memory block, so you can safely scroll within that region.
> - This should become an attribute of an IMemoryBlockExtension. i.e.
> (optionally) ensure the base address and size of a memory block are
> respected (and thus automatically set the rendering preferences)
>
> Stefan Bylund wrote:
>  
>
> > Hi,
> >
> > The Memory view reads a bunch of bytes before the specified base
> > address. This is bad for some kind of embedded systems and core dumps
> > where you have many small non-consecutive memory snapshots.
> >
> > The only way to make the Memory view work on such systems is to choose
> >    
>
>  
>
> > "Table Rendering Preferences..." in the Memory view's menu and
> > deselect "Automatically load next page of memory when scrolled to end
> >    
> of buffer".
>  
>
> > After that the Memory view respects the base address and does not try
> > to read a bunch of bytes before it. However, in this mode, you can not
> >    
>
>  
>
> > scroll down and automatically fetch more memory, which still can be
> >    
> useful.
>  
>
> > Would it be possible if the Memory view was changed so that it always
> > respects the base address? This would make it much more useful.
> >
> > Should I file a bug report on this?
> >
> >
> > Regards,
> > Stefan
> >
> >
> >    
>
> --
> Derek
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--
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Stefan Bylund
Senior Software Engineer
Enea
Skalholtsgatan 9,
Box 1033, SE-164 21 Kista, Sweden
Direct: +46 8 50 71 43 25
Mobile: +46 709 71 43 25
stefan.bylund@xxxxxxxx
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