06.08.2013 Views

pSOSystem System Calls - Read

pSOSystem System Calls - Read

pSOSystem System Calls - Read

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

as_catch pSOS+ <strong>System</strong> <strong>Calls</strong><br />

Target<br />

T_PREEMPT /<br />

T_NOPREEMPT<br />

T_TSLICE /<br />

T_NOTSLICE<br />

T_ASR /<br />

T_NOASR<br />

T_USER /<br />

T_SUPV<br />

T_ISR /<br />

T_NOISR<br />

User and Supervisor Modes<br />

ASR is / is not preemptible.<br />

ASR can / cannot be time-sliced.<br />

ASR nesting enabled/disabled.<br />

If T_ASR is set, then the ASR should be<br />

programmed to be re-entrant. If T_NOASR is set,<br />

the ASR is prevented from being re-entered as a<br />

result of another as_send() call made to that<br />

task.<br />

ASR runs in user mode / supervisor mode.<br />

See “User and Supervisor Modes” under<br />

“Target.”<br />

Interrupts are enabled / disabled while ASR<br />

runs.<br />

These options are available only on certain<br />

processors.<br />

“Target.”<br />

See “Interrupt Control” under<br />

You use the symbolic constants T_USER and T_SUPV on each processor as follows:<br />

PPC<br />

960<br />

x86<br />

T_LEVELMASK0<br />

through<br />

T_LEVELMASKn<br />

Certain interrupts are disabled while ASR runs.<br />

These options are available only on certain<br />

processors. See “Interrupt Control” under<br />

“Target.”<br />

On PowerPC, 960 and x86 processors, ASRs execute in supervisor<br />

mode only. Hence the symbolic constants T_USER and T_SUPV are<br />

ignored.<br />

1-4 <strong>pSO<strong>System</strong></strong> <strong>System</strong> <strong>Calls</strong>

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!