* Will ll/sc work from user space?
@ 2003-09-19 0:30 David Daney
2003-09-19 11:17 ` Maciej W. Rozycki
2003-09-19 20:11 ` Dominic Sweetman
0 siblings, 2 replies; 3+ messages in thread
From: David Daney @ 2003-09-19 0:30 UTC (permalink / raw)
To: linux-mips
Q: Will ll/sc instructions work from a linux user process ?
If so What happens if there is a context switch between the two?
What happens if the memory location is paged out and then back into a
different physical page?
Thanks in advance for any insight into this.
David Daney.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Will ll/sc work from user space?
2003-09-19 0:30 Will ll/sc work from user space? David Daney
@ 2003-09-19 11:17 ` Maciej W. Rozycki
2003-09-19 20:11 ` Dominic Sweetman
1 sibling, 0 replies; 3+ messages in thread
From: Maciej W. Rozycki @ 2003-09-19 11:17 UTC (permalink / raw)
To: David Daney; +Cc: linux-mips
On Thu, 18 Sep 2003, David Daney wrote:
> Q: Will ll/sc instructions work from a linux user process ?
Yep.
> If so What happens if there is a context switch between the two?
>
> What happens if the memory location is paged out and then back into a
> different physical page?
Then sc will fail.
--
+ Maciej W. Rozycki, Technical University of Gdansk, Poland +
+--------------------------------------------------------------+
+ e-mail: macro@ds2.pg.gda.pl, PGP key available +
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Will ll/sc work from user space?
2003-09-19 0:30 Will ll/sc work from user space? David Daney
2003-09-19 11:17 ` Maciej W. Rozycki
@ 2003-09-19 20:11 ` Dominic Sweetman
1 sibling, 0 replies; 3+ messages in thread
From: Dominic Sweetman @ 2003-09-19 20:11 UTC (permalink / raw)
To: David Daney; +Cc: linux-mips
David,
> Q: Will ll/sc instructions work from a linux user process ?
As Maciej says, yes.
> If so What happens if there is a context switch between the two?
The sc fails.
It fails whenever any interrupt or other exception (perhaps a VM
event, for example) happens after the ll but before the sc.
> What happens if the memory location is paged out and then back into a
> different physical page?
If that happens between the ll and the sc, then you must certainly
have got an interrupt.
--
Dominic Sweetman
MIPS Technologies
^ permalink raw reply [flat|nested] 3+ messages in thread
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2003-09-19 0:30 Will ll/sc work from user space? David Daney
2003-09-19 11:17 ` Maciej W. Rozycki
2003-09-19 20:11 ` Dominic Sweetman
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