RE: linux-xscale port, SYSFS device support

["Jeff Hill" <johill@lanl.gov>]

A patch (overlapping with the one provided below) for arm archetecture
impure little endian was provided earlier by Larry Doolittle. It was
integrated into EPICS R3.1.4.8. The preprocessor switch in that patch was
_armv4l_. In contrast, the patch below is using just __arm__).

http://www.d-tacq.com/swrel/EPICS/base-linux-xscale.patch

However, TBOMK config file changes for XSCALE have *not* yet been
integrated.

Jeff

> -----Original Message-----
> From: Peter Milne [mailto:Peter.Milne@d-tacq.com] 
> Sent: Tuesday, November 08, 2005 1:58 AM
> To: tech-talk@aps.anl.gov
> Subject: linux-xscale port, SYSFS device support
> 
> 
> Hi All
> 
> I've recently ported BASE 3.14.7 to run on linux-xscale (so that our 
> intelligent digitizers now have IOC functionality on board). 
> The patch to build the IOC is available here: 
> http://www.d-tacq.com/epics.shtml
> 
> The port was very straightforward, thanks to the excellent 
> EPICS build 
> system. If anyone is planning to repeat this exercise, the only issue 
> with xscale (and probably any little-endian ARM processor) on 
> Linux is 
> that the floating point library has another take on little-endianness 
> compared to the norm - easily corrected as shown in the patch.
> 
> A second point that may be of interest to list members is 
> Device Support 
> for Sysfs:
> 
> It's increasingly common in modern Linux systems to use 
> device files on 
> Sysfs to enable simple user space access to kernel 
> parameters. Or in our 
> case, to nail up a Linux VFS with a file per channel. I couldn't find 
> suitable Device Support for this functionality, so I wrote a 
> simple but 
> generic "dsSysfs" device support interface, using "ai" records and 
> encoding the location and characteristics of the files in the 
> INP field.
> 
> So, for example, it's easy to create records for
> 
> AI monitoring:
> field(INP, "@/dev/mean/01 rb4")     # reads the rolling mean 
> for channel 
> 01 as a 4 byte integer
> ...
> field(INP, "@/dev/mean/96 rb4")     # reads the rolling mean 
> for channel 
> 96 as a 4 byte integer
> 
> Heartbeat (generic to any Linux system) :
> field(INP, "@/proc/uptime")            # read the ascii data 
> from this file
> 
> or even
> 
> System health monitor:
> field(INP, "@#!sysmon -T 1")         # read the [ascii] result of 
> spawned task sysmon (temperature monitor).
> 
> The source code and doc is freely available at 
> http://www.d-tacq.com/epics.shtml
> 
> If there already is the means to do this in EPICS, do let me know, it 
> will be useful to compare features.
> 
> Thanks
> 
> Peter.
> 
> -- 
> Peter Milne			Peter.Milne@d-tacq.com
> D-TACQ Solutions Ltd		www.d-tacq.com
>