Revert back frame pointers for s390x (remove -fno-omit-framepointer but use -mbackchain)
Affects | Status | Importance | Assigned to | Milestone | ||
---|---|---|---|---|---|---|
Ubuntu on IBM z Systems |
New
|
Undecided
|
Unassigned | |||
dpkg (Ubuntu) | Status tracked in Oracular | |||||
Noble |
New
|
Undecided
|
Unassigned | |||
Oracular |
New
|
Undecided
|
Unassigned | |||
glibc (Ubuntu) | Status tracked in Oracular | |||||
Noble |
New
|
Undecided
|
Unassigned | |||
Oracular |
New
|
Undecided
|
Unassigned |
Bug Description
The preferred way of doing stack unwinding on Linux on Z is via dwarf call frame information.
In absence of a dwarf unwinder (as in the Linux kernel) a stack chain can be maintained at runtime in addition to the dwarf unwinding information.
This allows for simple backtrace implementations, but imposes a small runtime overhead. For this to work, all code that might be part of backtrace must be built with the -mbackchain GCC option.
The -fno-omit-
Having a (soft/simulated) frame pointer does not improve backtraces at all on IBM Z.
However, forcing a frame pointer via the -fno-omit-
Given -fno-omit-