When javaFrameAnchor::_last_Java_sp == NULL for a non-first entry frame

[Hiroshi Yamauchi]

Hi,

In AsyncGetCallTrace, I observe

  javaFrameAnchor::_last_Java_sp == NULL

in non-first entry frames on Linux/x86. It is the condition for the
entry frame to be a first frame. So, I get truncated stack traces
because stack walk stops at the false first frame.

I thought that the contract was that the _last_Java_sp != NULL for all
non-first entry frames. Is it correct?

Strangely I see the behavior on one Linux environment (kernel, libc,
other libraries) but not on another Linux environment (Ubuntu). But
I'm not sure how the environment could affect the _last_Java_sp field.

Does it ring anyone's bell?

thanks.

Hiroshi