[ubuntu-mono] [Bug 667225] Re: [armel] Thumb builds cause defective Mono 2.8 builds (SIGILL on NullReferenceException)

[Julian Brown]

Thanks for the update -- I hadn't got very far with reproducing this
anyway!

-- 
[armel] Thumb builds cause defective Mono 2.8 builds (SIGILL on NullReferenceException)
https://bugs.launchpad.net/bugs/667225
You received this bug notification because you are a member of Ubuntu
CLI/Mono Uploaders, which is subscribed to mono in ubuntu.

Status in Linaro GCC: Invalid
Status in “gcc-4.4” package in Ubuntu: New
Status in “gcc-4.5” package in Ubuntu: New
Status in “mono” package in Ubuntu: New

Bug description:
Binary package hint: gcc-4.5

It seems there is a problem with the Linaro patches to GCC.

Unmodified upstream Mono 2.8 builds with gcc-4.4 or gcc-4.5 (for 4.5, see attached for a minor build fix). However, using the Ubuntu (Linaro) compilers results in a Mono runtime which fails during the test suite when catching a NullReferenceException. Poking about with gdb implies it's an issue with SIGILL, specifically with Thumb instructions like LSLS in the wrong place.

Ubuntu gcc-4.4 and gcc-4.5 are defective here, but Debian gcc-4.4 and gcc-4.5 are fine. Significantly, gcc-4.5 in both cases is supposedly the same upstream version (4.5.1), but the Linaro-patched package in Ubuntu fails. This bug makes it impossible to update Mono in Natty.