<div dir="ltr">Following Paul's idea, what happens in both the NIF and your minimal C program if you first launch a new thread and call the API from there?</div><br><div class="gmail_quote"><div dir="ltr">On Mon, Apr 17, 2017 at 5:52 PM Fisher, Paul <<a href="mailto:pfisher@alertlogic.com">pfisher@alertlogic.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div style="direction:ltr">Complete wild guess, but is there a difference in nif initialization running off the main thread in non-working version? This would be a problem for some low-level Mach related things. Not near laptop to look through the code to see
if that changed.</div>
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<div id="m_-2395972316349742208x_divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" color="#000000" style="font-size:11pt"><b>From:</b> <a href="mailto:erlang-questions-bounces@erlang.org" target="_blank">erlang-questions-bounces@erlang.org</a> <<a href="mailto:erlang-questions-bounces@erlang.org" target="_blank">erlang-questions-bounces@erlang.org</a>> on behalf of Igor Clark <<a href="mailto:igor.clark@gmail.com" target="_blank">igor.clark@gmail.com</a>><br>
<b>Sent:</b> Monday, April 17, 2017 4:38:11 PM<br>
<b>To:</b> <a href="mailto:erlang-questions@erlang.org" target="_blank">erlang-questions@erlang.org</a><br>
<b>Subject:</b> [erlang-questions] NIF+device problem moving R18->R19 / Mac 10.11->10.12</font>
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<div class="m_-2395972316349742208PlainText"></div></span></font></div><div><font size="2"><span style="font-size:10pt"><div class="m_-2395972316349742208PlainText">Hi all,<br>
<br>
I'm having problems updating a NIF to work correctly with R19 and/or <br>
MacOS Sierra (10.12). The NIF uses Mac OS C API calls to talk to some <br>
hardware. It's been working just fine with R18 on El Capitan, but it <br>
fails in a manner I don't understand when I trying to run it on R19 or <br>
Sierra. I'm pretty baffled as to what's going on, and wonder if any of <br>
the following might ring bells or set off a spider-sense for anyone here?<br>
<br>
- The code continues to work 100% as expected on R18 / Mac OS El Capitan <br>
(10.11), as it has for the last year or so.<br>
<br>
- On R19 on El Capitan, 99% of the C code works as before, but one <br>
particular MacOS C API call fails unexpectedly. It doesn't crash or <br>
cause errors directly, but it returns null instead of a valid value as <br>
before. There are no build errors or warnings. (I'm using 'pc' plugin <br>
version 1.5.0 with rebar3). Other MacOS API calls talking to the same <br>
hardware work as expected, sending correct commands, getting the <br>
hardware to carry out operations as expected and returning expected <br>
values, without any problems.<br>
<br>
- On both R18 & R19 on Sierra, exactly the same problem occurs as above <br>
in R19 on El Capitan.<br>
<br>
- If I make the failing/null-returning OS API call in a plain, <br>
simple-as-possible C file compiled with gcc (Apple LLVM/clang), it works <br>
as expected, *on both OS versions*.<br>
<br>
- If I paste that same simple-as-possible C code verbatim into the NIF, <br>
as the first line in the load() function, and run it on R18/El Capitan, <br>
it continues to work as expected.<br>
<br>
- If I then try to run that identical pasted-verbatim NIF code with no <br>
changes on R18/Sierra or on R19 & either OS version, this one particular <br>
function call fails, as above.<br>
<br>
I realise it could be many things, and my initial thought was that it <br>
must be the OS change or even the hardware failing - but the hardware <br>
and C API call continue to work just fine on both OS versions when the <br>
NIF stuff is taken out of the picture, and on El Capitan, the <br>
previously-not-happening problem reliably (and only) starts happening <br>
when I switch from R18 to R19.<br>
<br>
Did anything change between R18 and R19 that might somehow make some, <br>
but not all, external C function calls fail on El Capitan/clang 8.0.0? <br>
And could that be something that also makes the same thing happen on <br>
both R18 and R19 under Sierra/clang 8.1.0? Could it perhaps be something <br>
do with the port compiler & LD/CXX flags?<br>
<br>
Any ideas as to where else I could look to try to track this down, or <br>
what might be causing this?<br>
<br>
(BTW, I'm using homebrew erlang, and I've tried all the above with <br>
versions 18.1, 18.3, 19.0.2 and 19.3 on both OS versions. The gcc/clang <br>
version on El Capitan is from Xcode 8.1, "Apple LLVM version 8.0.0 <br>
(clang-800.0.42.1)". On Sierra it's from Xcode 8.3.1, "Apple LLVM <br>
version 8.1.0 (clang-802.0.41)" - but as above, the plain/non-NIF C code <br>
works perfectly and identically on both versions.)<br>
<br>
Thanks very much,<br>
Igor<br>
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