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<== Date ==> <== Thread ==>

Subject: Re: CA on alphas
From: Marty Kraimer <mrk@aps.anl.gov>
To: epics tech-talk <TECH-TALK@aps.anl.gov>
Date: Thu, 11 Feb 1999 10:40:07 -0600
Geoff Savage wrote:
> 
> To get running on our alphas I grabbed the compiled libraries and binaries
> for the alpha from Mark Rivers web site.  Thanks :) These are for EPICS
> R3.12.  While using these I have encountered an interesting problem.  I
> receive unaligned access errors from ca_array_put().  I traced them back to
> issue_ca_array_put() in access.c.  When pdest and pvalue are incremented by
> size_of_one.  At this point dbr_long_t has a size of 4 bytes (epicsInt32).
> A long on an alpha is 8 bytes.  When the assignment is made between the two
> arrays the type of long is used.  size_of_one needs to be 8 bytes.
> 
> I'm looking at R3.13.beta11 code.
> 
> Any suggestions.  The problem will appear when an extra 4 bytes is written
> at the end of pdest.

The problem is the structures in db_access.h. They described the data that is
passed across the network. They assume a 32 bit architecture. CA does take care
of byte order. My guess is that it may take a lot of work to properly support 64
bit architectures.


Marty Kraimer

References:
CA on alphas Geoff Savage

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