Re: What is the preferred way of doing a context switch on the ARM?
- From: Michael <MichaelDMcDonnell@xxxxxxxxx>
- Date: Fri, 29 Aug 2008 06:39:06 -0700 (PDT)
On Aug 29, 1:05 am, "Boudewijn Dijkstra" <boudew...@xxxxxxxxx> wrote:
Op Fri, 29 Aug 2008 07:45:34 +0200 schreef Michael
<MichaelDMcDonn...@xxxxxxxxx>:
I’m asking, because I see no clean way to do it. On stack based
machines you simply “pushall” onto the active task’s stack, switch
stacks, and do a “popall”. The ARM makes this difficult because when
it switches to a privileged mode, the active task’s stack becomes
“invisible”, and the CPSR gets saved into the SPSR (as opposed to
being pushed onto the stack). Thanks!
User-defined task code is only run in User or System mode, which both use
the 'unaliased' registers. On an exception, the processor starts using
alternative registers, but you can go to System mode to access those
unaliased registers and push them (and the SPSR as well, of course).
--
Gemaakt met Opera's revolutionaire e-mailprogramma: http://www.opera.com/mail/
Yes, but I was looking for a clean way to do it (no mode changing).
Also there's the question of what register to use for the STM / LDM
instructions. Evidently you need to push a register onto the privilege
mode's stack. I would think that there would be a cleaner way...
.
- Follow-Ups:
- Re: What is the preferred way of doing a context switch on the ARM?
- From: Boudewijn Dijkstra
- Re: What is the preferred way of doing a context switch on the ARM?
- References:
- What is the preferred way of doing a context switch on the ARM?
- From: Michael
- Re: What is the preferred way of doing a context switch on the ARM?
- From: Boudewijn Dijkstra
- What is the preferred way of doing a context switch on the ARM?
- Prev by Date: Re: Where is the ARM Instruction Set Manual? (the one with bit field encodings)
- Next by Date: Re: What is the preferred way of doing a context switch on the ARM?
- Previous by thread: Re: What is the preferred way of doing a context switch on the ARM?
- Next by thread: Re: What is the preferred way of doing a context switch on the ARM?
- Index(es):
Relevant Pages
|
