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Re: Problem with longjmp on A9

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In message <ac6ff5ef51.Matthew@sinenomine.freeserve.co.uk>
          Matthew Phillips <spam2011m@yahoo.co.uk> wrote:

> I have been trying to track down a difficult bug in my software which only
> affects users of the A9Home computer, specifically an A9 running "RISC OS
> Select 4.42 kernel 8.68".  The Shared C Library version is "5.59 (04 Mar
> 2006) 32bit only".  The same user has a RISC PC with Select 6.10 kernel 10.49
> and Shared C Library "5.63 (11 Mar 2007) 26bit only" on which the problem
> does not occur.  It does not occur on the Iyonix or Beagleboard either.

> After investigating, I can only conclude that the A9's Shared C Library is
> not fully restoring the context saved at setjmp when a subsequent longjmp is
> executed.  Let me set out my reasoning and if anyone finds any holes in it,
> please let me know.

That is a known problem that I have reported to Ad6/ROL in 2006. 
longjmp is indeed broken on the current A9home ROM image (Select 4.42, 
CLib 5.59), but also on the previous A9home ROM image (which had CLib 
5.02).

That problem affects the exception handling in Easi/TechWriter and can 
lead to arbitrary failures of these applications on the A9home. That 
is the reason why I still advise users in the documentation that EW/TW 
has beta status on the A9home.

> Has anyone else had this sort of behaviour?  Are there any alternative
> explanations before I take this up with ROL?

> I'm not very familiar with the A9: would it be possible (or indeed advisable)
> to softload a different version of the Shared C Library?

Yes, that should be possible. It was not an option in 2006 because 
there was no such version available for public distribution (the 
softload CLib for the Iyonix could not be used), but it should be easy 
enough nowadays to build a suitable CLib from the ROOL sources.

-- 
Martin
---------------------------------------------------------------------
Martin Wuerthner         MW Software      http://www.mw-software.com/
        RISC OS Software for Design, Printing and Publishing
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Thread

Problem with longjmp on A9 Matthew Phillips <spam2011m@yahoo.co.uk> - 2011-07-09 07:31 +0100
  Re: Problem with longjmp on A9 wpb <willblatchley@yahoo.com> - 2011-07-10 21:20 -0700
    Re: Problem with longjmp on A9 David Pitt <pittdj@pittdj.co.uk> - 2011-07-11 07:28 +0100
  Re: Problem with longjmp on A9 Martin Wuerthner <spamtrap@mw-software.com> - 2011-07-11 11:39 +0200
    Re: Problem with longjmp on A9 David Pitt <pittdj@pittdj.co.uk> - 2011-07-12 07:23 +0100
      Re: Problem with longjmp on A9 Matthew Phillips <spam2011m@yahoo.co.uk> - 2011-07-12 21:15 +0100

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