Re: How do I get rid of a memory hole(in cortexm0plus)?

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.arch.embedded
Subject	Re: How do I get rid of a memory hole(in cortexm0plus)?
Date	2016-10-31 14:24 +0100
Organization	A noiseless patient Spider
Message-ID	<nv7gl8$rob$1@dont-email.me> (permalink)
References	(2 earlier) <nv72j0$cog$1@dont-email.me> <e6dfb86c-3eb6-40ee-8917-eeb4ebe6a310@googlegroups.com> <nv75dc$lh9$2@dont-email.me> <d3f03202-43c6-4075-9c5e-c8fc350300e1@googlegroups.com> <ecbed88e-aec1-43cc-957f-7ea20f35071f@googlegroups.com>

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On 31/10/16 13:23, Jack wrote:
> Il giorno lunedì 31 ottobre 2016 13:11:15 UTC+1, Jack ha scritto:
> 
>>> Certainly you can use the linker file to place the flash configuration
>>> segment somewhere else.  But then it will not work as the flash
>>> configuration - because the Kinetis reads the values are addresses 0x400
>>> to 0x40f at reset, with a total disregard for whatever linker file you
>>> use.  The issue is the Kinetis hardware, not the linker file.
>>
>> If it's HW then ok, didn't know that.
>> If on the other hand is a value hardcoded in the startup routine then it can be changed...
> 
> just checked, it's really HW. anyway I find odd that they put it at 0x400...
> 

Well, the interrupt vectors are hard-coded at 0x0, so 0x400 is the start
of the next 1K block that was available.

The idea works quite well, except for one mind-bogglingly stupid
decision.  Erasing that area (setting it all to 0xff) locks the device
and its flash.  To /unlock/ it, so that you can program the thing with
real code, you have to first program byte 0x40f to 0xfe.  It is an
insane idea that makes it easy to accidentally brick your devices if you
are using simple standard ARM JTAG tools, and offers no benefits whatsoever.

Apart from that, the Kinetis devices are very nice chips.

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Thread

How do I get rid of a memory hole(in cortexm0plus)? Johann Klammer <klammerj@NOSPAM.a1.net> - 2016-10-30 09:29 +0100
  Re: How do I get rid of a memory hole(in cortexm0plus)? David Brown <david.brown@hesbynett.no> - 2016-10-30 16:50 +0100
  Re: How do I get rid of a memory hole(in cortexm0plus)? Jack <jack4747@gmail.com> - 2016-10-31 01:16 -0700
    Re: How do I get rid of a memory hole(in cortexm0plus)? David Brown <david.brown@hesbynett.no> - 2016-10-31 10:24 +0100
      Re: How do I get rid of a memory hole(in cortexm0plus)? Jack <jack4747@gmail.com> - 2016-10-31 02:43 -0700
        Re: How do I get rid of a memory hole(in cortexm0plus)? David Brown <david.brown@hesbynett.no> - 2016-10-31 11:12 +0100
          Re: How do I get rid of a memory hole(in cortexm0plus)? Jack <jack4747@gmail.com> - 2016-10-31 05:11 -0700
            Re: How do I get rid of a memory hole(in cortexm0plus)? Jack <jack4747@gmail.com> - 2016-10-31 05:23 -0700
              Re: How do I get rid of a memory hole(in cortexm0plus)? David Brown <david.brown@hesbynett.no> - 2016-10-31 14:24 +0100

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