On 17-01-12 11:26:06, Dave Martin wrote:

Currently the vector length is inherited across both fork() and
exec().

Inheritance across fork() is desirable both for creating a copy of
a process (traditional fork) or creating a thread (where we want
all threads to share the same VL by default).

Inheritance across exec() is less desirable, because of the ABI
impact of large vector lengths on the size of the signal frame --
when running a new binary, there is no guarantee that the new
binary is compatible with these ABI changes.

This flag makes the vector length non-inherited by default.

Can we make vector length inherited across fork but non-inherited
across exec by default?

Instead, the vector length is reset to a system default value,
unless the THREAD_VL_INHERIT flag has been set for the thread.

THREAD_VL_INHERIT is currently sticky: i.e., if set, it gets
inherited too.  This behaviour may be refined in future if it is
not flexible enough.

-- 
Yao (??)