Some problems with the libbsd update
sebastian.huber at embedded-brains.de
Wed Aug 22 11:47:28 UTC 2018
On 22/08/18 13:44, Joel Sherrill wrote:
> On Wed, Aug 22, 2018, 4:51 AM Sebastian Huber
> <sebastian.huber at embedded-brains.de
> <mailto:sebastian.huber at embedded-brains.de>> wrote:
> On 22/08/18 09:50, Sebastian Huber wrote:
> > To support everything in RTEMS is a lot of work, so I have to make
> > some trade-offs. The implementation of this API must be as
> > as possible since it is used in the critical paths of the network
> > stack. I will try to use a single global epoch and thread-specific
> > records as suggested by Matthew Macy to avoid the need for
> > per-processor data structures and the thread pinning. One key
> issue is
> > that epoch records must not be destroyed:
> > https://www.mankier.com/3/ck_epoch_register
> > The consequence of this is that unlimited thread objects may
> lead to
> > undefined behaviour with this implementation approach. Also
> > thread-local storage cannot be used since it is reinitialized
> once a
> > thread restarted or reused. The epoch record must be included in
> > Thread_Control and must not be touched by _Thread_Initialize().
> > means I have to move the API and its implementation along with the
> > Concurrency Kit to RTEMS.
> Ok, there is also an
> This allows a localized implementation in libbsd.
> Due to performance reasons this requires the use of thread-local
> storage. Any objections to make thread-local storage a hard
> for libbsd support?
> Not particularly but there should be an effort to identify which
> targets do not have TLS support yet. Other than sparc, arm, powerpc
> and i386, I don't know the status. Sounds like a series of tickets.
TLS is also supported on m68k and riscv. Are the other targets
maintained at all?
Sebastian Huber, embedded brains GmbH
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