[Vm-dev] [ANN] ARM Stack VMs available

[Douglas McPherson]

Hi Ken,

> On Nov 11, 2014, at 16:28, Ken Dickey <Ken.Dickey at whidbey.com> wrote:
> 
> 
> On Sun, 9 Nov 2014 20:56:47 -0800
> Douglas McPherson <djm1329 at san.rr.com> wrote:
> 
> KenD>>
>>> The stkspurlinuxhtARM VM, however, complains:
>>> This interpreter (vers. 6521) cannot read image file (vers. 6505).
>>> 
>>> I presume some conversion is required to get the image into SPUR format?
>>> 
>> Yes, the Spur VMs require a new image format. There are recent Squeak trunk images in the spur format on Eliot’s site. I’ll let Eliot and others comment about how a Cuis image might be converted. 
> 
> I tried out the Squeak SPUR image from the Cog site and everything Squeak seems fine.
> 
> 
> There is a timing bug with Cuis redraw that shows up on both the stklinuxhtARM vm and the one you sent me earlier. 
> 
> Basically, I am using DisplayObject>>slideFrom:to:nSteps:delay: to do some animation.  When multiple timer events fire during an animation it sometimes appears that the x,y redraw origin is used from the currently drawing morph's position, not 0,0.  I.e. part of the redisplay is offset.  [Display redraw via menu corrects the display].
> 
> This _only_ happens on the Samsung ARM Chromebook, never on Intel CPUs.  
> 

Thanks for reporting this. I’ll try to look into it. There are definitely ARM-specific changes to support certain atomic operations, so there may be something not quite right with these. 

Can you suggest a method for reproducing this in Squeak? I repeatedly sent morphs to the trash (with appropriate preference set to enable the animation) but didn’t see an issue. I suspect I’m not driving it hard enough.  

> My life is really, really busy right now, so I have never had time to dig into this.  I can redraw the display, so a workaround exists.
> 
> [One possible resource.  The Apache Portable Runtime, http://apr.apache.org/ , implements compareAndSwap and various other atomic operations across various OSs.]
> 

Thanks for the reference. It may be useful. I also found a library called Mintomic (http://preshing.com/20130505/introducing-mintomic-a-small-portable-lock-free-api/) which may help.

> I am happy to do quick tests, but must apologize for lack of time to dig into this.
> 

No problems, and thanks again for reporting it. 


> FYI,
> -KenD