Real-time shadow services.

Collaboration diagram for Real-time shadow services.:

Files
file	shadow.c
	Real-time shadow services.

Functions
int	xnshadow_harden (void)
	Migrate a Linux task to the Xenomai domain. More...
void	xnshadow_relax (int notify, int reason)
	Switch a shadow thread back to the Linux domain. More...
int	xnshadow_map (xnthread_t *curr, xncompletion_t __user *u_completion, unsigned long __user *u_mode_offset)
	Create a shadow thread context. More...
xnshadow_ppd_t *	xnshadow_ppd_get (unsigned muxid)
	Return the per-process data attached to the calling process. More...

Detailed Description

Real-time shadow services.

Function Documentation

int xnshadow_harden

(

void

)

Migrate a Linux task to the Xenomai domain.

This service causes the transition of "current" from the Linux domain to Xenomai. This is obtained by asking the gatekeeper to resume the shadow mated with "current" then triggering the rescheduling procedure in the Xenomai domain. The shadow will resume in the Xenomai domain as returning from schedule().

Environments:

This service can be called from:

• User-space thread operating in secondary (i.e. relaxed) mode.

Rescheduling: always.

References xnsched::curr, XNATOMIC, XNDEBUG, xnpod_dispatch_signals(), XNRELAX, and xnshadow_relax().

Referenced by xnshadow_map().

int xnshadow_map	(	xnthread_t *	curr,
		xncompletion_t __user *	u_completion,
		unsigned long __user *	u_mode_offset
	)

Create a shadow thread context.

This call maps a nucleus thread to the "current" Linux task. The priority and scheduling class of the underlying Linux task are not affected; it is assumed that the interface library did set them appropriately before issuing the shadow mapping request.

Parameters

thread	The descriptor address of the new shadow thread to be mapped to "current". This descriptor must have been previously initialized by a call to xnpod_init_thread().
u_completion	is the address of an optional completion descriptor aimed at synchronizing our parent thread with us. If non-NULL, the information xnshadow_map() will store into the completion block will be later used to wake up the parent thread when the current shadow has been initialized. In the latter case, the new shadow thread is left in a dormant state (XNDORMANT) after its creation, leading to the suspension of "current" in the Linux domain, only processing signals. Otherwise, the shadow thread is immediately started and "current" immediately resumes in the Xenomai domain from this service.

References xnheap_alloc(), XNMAPPED, XNOTHER, xnpod_start_thread(), xnpod_suspend_thread(), XNPRIOSET, XNRELAX, XNSHADOW, and xnshadow_harden().

xnshadow_ppd_t* xnshadow_ppd_get

(

unsigned

muxid

)

Return the per-process data attached to the calling process.

This service returns the per-process data attached to the calling process for the skin whose muxid is muxid. It must be called with nklock locked, irqs off.

See xnshadow_register_interface() documentation for information on the way to attach a per-process data to a process.

Parameters

muxid

the skin muxid.

Returns

the per-process data if the current context is a user-space process;

NULL otherwise.

void xnshadow_relax	(	int	notify,
		int	reason
	)

Switch a shadow thread back to the Linux domain.

This service yields the control of the running shadow back to Linux. This is obtained by suspending the shadow and scheduling a wake up call for the mated user task inside the Linux domain. The Linux task will resume on return from xnpod_suspend_thread() on behalf of the root thread.

Parameters

notify	A boolean flag indicating whether threads monitored from secondary mode switches should be sent a SIGDEBUG signal. For instance, some internal operations like task exit should not trigger such signal.
reason	The reason to report along with the SIGDEBUG signal.

Environments:

This service can be called from:

• User-space thread operating in primary (i.e. harden) mode.

Rescheduling: always.

Note

"current" is valid here since the shadow runs with the properties of the Linux task.

References xnsched::curr, XNAFFSET, xnpod_suspend_thread(), XNPRIOSET, XNRELAX, XNROOT, and XNTRAPSW.

Referenced by pthread_set_mode_np(), xnpod_trap_fault(), and xnshadow_harden().