Hi Paul,
On 8/30/05, Paul Duplys <kernel_newbie@xxxxxx> wrote:
> Hi Ohad,
>
> the architecture I'm working on, Infineon's Tricore microcontroller, has 16
> general purpose data registers and 16 general purpose address registers (pc,
> psw and so on are kept in special core registers). So I guess I have enough
> registers to sacrifice one for holding the "current" value.
>
> You wrote:
> > Hi Paul,
> > I'll give you two examples:
> > On PPC the current is simply defined as the register r2.
> > quoting from a vanilla 2.6.11 here (Linux/include/asm-ppc/current.h ) :
> > register struct task_struct *current asm ("r2");
> >
>
> Then there must be a function (or an instruction in a function), which
> stores the pointer to the current task_struct in the register r2, right? Do
> you know, where that function/instruction can be found in kernel code, so I
> can modify it for my register set?
this function is very architecture dependant, is implemented in pure assembly,
and is located, on PPC,for example, in "arch/ppc/kernel/entry.S".
its beginning is marked by _GLOBAL(_switch), it's not short, but I guess
what you're looking for are the following lines:
/* save the old current 'last' for return value */
mr r3,r2
addi r2,r4,-THREAD /* Update current */
note: on entry, r4 points to the THREAD for the new task.
hope it helps,
Ohad.
>
> Thanks for your help,
> Paul
>
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