- after a trap to kernel, the code automatically switches to kernel
stack, in the future local to the CPU
- k_reenter variable replaced by a test whether the CS is kernel cs or
not. The information is passed further if needed. Removes a global
variable which would need to be cpu local
- no need for global variables describing the exception or trap
context. This information is kept on stack and a pointer to this
structure is passed to the C code as a single structure
- removed loadedcr3 variable and its use replaced by reading the %cr3
register
- no need to redisable interrupts in restart() as they are already
disabled.
- unified handling of traps that push and don't push errorcode
- removed save() function as the process context is not saved directly
to process table but saved as required by the trap code. Essentially
it means that save() code is inlined everywhere not only in the
exception handling routine
- returning from syscall is more arch independent - it sets the retger
in C
- top of the x86 stack contains the current CPU id and pointer to the
currently scheduled process (the one right interrupted) so the mode
switch code can find where to save the context without need to use
proc_ptr which will be cpu local in the future and therefore
difficult to access in assembler and expensive to access in general
- some more clean up of level0 code. No need to read-back the argument
passed in
%eax from the proc structure. The mode switch code does not clobber
%the general registers and hence we can just call what is in %eax
- many assebly macros in sconst.h as they will be reused by the apic
assembly
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