runtime: darwin/arm lldb needs to pass SIGSEGV

[crawshaw]

The darwin/arm builder runs programs via lldb. (It is the only way to remotely dial the device running the binary.) The debugger likes to intercept signals that Go needs for normal operation. For example, there is a hidden panic inside the html/template tests that jams lldb. The obvious command does not work:

process handle SIGSEGV --stop false --pass true --notify false

It looks like passing on these signals may not be supported yet:

http://lists.cs.uiuc.edu/pipermail/lldb-dev/2013-July/002009.html

[minux]

could we simply supply a stream of "continue" command to lldb? or make lldb do "continue" upon reception of the SIGSEGV signal (gdb can do "catch signal SIGSEGV", and then we can define command to be executed when SIGSEGV is received.)

[crawshaw]

I tried that manually. Giving lldb a continue instruction does not seem to work. (Even several times.)

[crawshaw]

LLDB engineer says its a long standing OS X bug and recommends we work around it:

https://llvm.org/bugs/show_bug.cgi?id=22868