Hello "schedule: re-entered unsafely."
After compiling the following program on ARM:
```hs
main = putStrLn "Hello, world!"
```
using `ghc hello.hs` I receive the following error when running the compiled code:
```
$ ./hello
hello: schedule: re-entered unsafely.
Perhaps a 'foreign import unsafe' should be 'safe'?
```
I'm trying to get GHC running on my Raspberry Pi 2, running Raspbian Jessie Light, which can be found here:
https://www.raspberrypi.org/downloads/raspbian/
I was following the instructions for installing the compiler on a freshly flashed RPI2 from here:
http://statusfailed.com/blog/2015/11/29/haskell-and-servant-on-scaleway-arm-servers.html
This was using the Linux ARMv7 binaries:
https://www.haskell.org/ghc/download_ghc_7_10_3\#linux_armv7
https://www.haskell.org/ghc/download_ghc_7_10_2\#linux_armv7
Additionally trying to upgrade cabal with `cabal install cabal-install` seems to hang forever. It gets stuck in various Setup.hs files and doesn't seem to progress. No CPU is taken up using this.
Some summary information:
> - llvm 3.5
> - gcc 4.9.2
> - original GHC from Raspbian is 7.6.3
> - cabal-install from Raspbian is 1.20.0.3
> - cabal is 1.20.0.2
> - This same problem affects both 7.10.2, and 7.10.3
<details><summary>Trac metadata</summary>
| Trac field | Value |
| ---------------------- | ------------ |
| Version | 7.10.2 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | #951 |
| Blocking | |
| CC | |
| Operating system | |
| Architecture | |
</details>
<!-- {"blocked_by":[],"summary":"Hello \"schedule: re-entered unsafely.\"","status":"New","operating_system":"","component":"Compiler","related":[951],"milestone":"","resolution":"Unresolved","owner":{"tag":"Unowned"},"version":"7.10.2","keywords":[],"differentials":[],"test_case":"","architecture":"","cc":[""],"type":"Bug","description":"After compiling the following program on ARM:\r\n\r\n{{{#!hs\r\nmain = putStrLn \"Hello, world!\"\r\n}}}\r\n\r\nusing `ghc hello.hs` I receive the following error when running the compiled code:\r\n\r\n{{{\r\n$ ./hello\r\nhello: schedule: re-entered unsafely.\r\n Perhaps a 'foreign import unsafe' should be 'safe'?\r\n}}}\r\n\r\nI'm trying to get GHC running on my Raspberry Pi 2, running Raspbian Jessie Light, which can be found here:\r\n\r\nhttps://www.raspberrypi.org/downloads/raspbian/\r\n\r\nI was following the instructions for installing the compiler on a freshly flashed RPI2 from here:\r\n\r\nhttp://statusfailed.com/blog/2015/11/29/haskell-and-servant-on-scaleway-arm-servers.html\r\n\r\nThis was using the Linux ARMv7 binaries:\r\n\r\nhttps://www.haskell.org/ghc/download_ghc_7_10_3#linux_armv7\r\nhttps://www.haskell.org/ghc/download_ghc_7_10_2#linux_armv7\r\n\r\nAdditionally trying to upgrade cabal with `cabal install cabal-install` seems to hang forever. It gets stuck in various Setup.hs files and doesn't seem to progress. No CPU is taken up using this.\r\n\r\nSome summary information:\r\n - llvm 3.5\r\n - gcc 4.9.2\r\n - original GHC from Raspbian is 7.6.3\r\n - cabal-install from Raspbian is 1.20.0.3\r\n - cabal is 1.20.0.2\r\n - This same problem affects both 7.10.2, and 7.10.3","type_of_failure":"OtherFailure","blocking":[]} -->
issue