It's about whether it's cleared entering a signal handler or not https://lkml.org/lkml/2008/3/5/207 https://lkml.org/lkml/2008/3/5/207 is the first message.

It's about whether it's cleared entering a signal handler or not https://lkml.org/lkml/2008/3/5/207 https://lkml.org/lkml/2008/3/5/207 is the first message. Basically: ABI implementation bug in kernel. https://lkml.org/lkml/2008/3/5/231 https://lkml.org/lkml/2008/3/5/231 GCC started actually relying on the ABI being correct in version 4.3, folks noticed bug.