Linux ARM, does schedule() jumps to user space ?
Hi, A very basic question. AFAIK schedule() selects the next process to run. Now once it has selected the process, and say if the process is a user space or kernel space one. how does the switch to user happens, a) Is it in schedule function . it has to be a arch level function called from schedule() b) or Else where, so is there a umberlla function like somefunc() { task_ptr = schedule(); switch_to(task_ptr) ... } Can someone explain this
Hi MJ, The switch_to(prev, next) function stores the registers of task "prev" to its kernel stack, than restores registers of task "next" from its kernel stack than resumes task "next" in kernel mode. If the selected task is a user process, it just takes the "return to user" path to user space. Regards, MH On Fri, Jan 3, 2014 at 6:31 PM, Mj Embd <mj.embd@gmail.com> wrote:
Hi,
A very basic question. AFAIK schedule() selects the next process to run. Now once it has selected the process, and say if the process is a user space or kernel space one. how does the switch to user happens,
a) Is it in schedule function . it has to be a arch level function called from schedule()
b) or Else where, so is there a umberlla function like
somefunc() { task_ptr = schedule(); switch_to(task_ptr)
...
}
Can someone explain this
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On Fri, Jan 3, 2014 at 4:35 PM, Miles MH Chen <orca.chen@gmail.com> wrote:
Hi MJ,
The switch_to(prev, next) function stores the registers of task "prev" to its kernel stack, than restores registers of task "next" from its kernel stack than resumes task "next" in kernel mode. How is the switch_to() function called from schedule ? or what is the umberella function which calls switch_to
What is the flow in which schedule and switch_to is called
If the selected task is a user process, it just takes the "return to user" path to user space.
Regards, MH
On Fri, Jan 3, 2014 at 6:31 PM, Mj Embd <mj.embd@gmail.com> wrote:
Hi,
A very basic question. AFAIK schedule() selects the next process to run. Now once it has selected the process, and say if the process is a user space or kernel space one. how does the switch to user happens,
a) Is it in schedule function . it has to be a arch level function called from schedule()
b) or Else where, so is there a umberlla function like
somefunc() { task_ptr = schedule(); switch_to(task_ptr)
...
}
Can someone explain this
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-- -mj
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