Re: Mach context switch

[Vasily Sartakov <sartakov@ksyslabs.org>]

ohh, thanks. its a correct. i setted up in set_user_regs context on binary module, and then they started. 
but i still dont make other kernel threads. when context_switch from one kernel_thread to another (for example, when thread_sleep acquire, and first in list idle_thread), anytime will be called swap_function? 
and i made in boot_script_exec_cmd a kernel_thread for user_bootstrap instead of thread_create+thread_start (no doswapin), because i have a kernel_stack=0, and cant run user_bootstrap. i think its not corrent (my solution), should i do it on active_stack ? 

thanks for answers.

>  1. when thread_call in bootstrap.c called, context switch acquire. and
>  im looked on x86 sources, and dont see when CPU should switch in
>  different mode for correct context switching. any help?

Note that usually one doesn't explicitly switch to user mode, but do as
if one returns to user mode. In bootstrap.c, see the “Exit to user
thread” comment above thread_bootstrap_return, implemented in entry.S:
“Called as a function, makes the current thread return from the kernel
as if from an exception.”, i.e. build_args_and_stack()/set_user_regs()
have prepared the context of a stack looking just like the first thing
the processus has done was to take a trap.