Re: tagging freebios2 tree

Li-Ta Lo  writes:
> On Tue, 2004-08-24 at 19:07, Eric W. Biederman wrote:
> > No quite I put the cpu_info structure at the bottom of the stack,
> > and this function looks it up.
> >
> > The same idea has been used in the kernel for quite a while.
> >
> > Basically this allows me to preallocate some per cpu information
> > and to pass that into cpu_initialize from another cpu.
> >
> > The linux kernel has been doing something similar for quite a while.
>
> Does cpu_info() return different value depends on which CPU it is 
> running ?

Yes.  The stack is per cpu and it returns a fixed address from
the stack structure.
> Are the data structures per CPU or shared between CPUs ?

per-cpu.  Which is the point.

Eric

tagging freebios2 tree

[Li-Ta Lo]

On Tue, 2004-11-02 at 18:06, Eric W. Biederman wrote:
> Li-Ta Lo  writes:
> > On Tue, 2004-08-24 at 19:07, Eric W. Biederman wrote:
> > > No quite I put the cpu_info structure at the bottom of the stack,
> > > and this function looks it up.
> > >
> > > The same idea has been used in the kernel for quite a while.
> > >
> > > Basically this allows me to preallocate some per cpu information
> > > and to pass that into cpu_initialize from another cpu.
> > >
> > > The linux kernel has been doing something similar for quite a while.
> >
> > Does cpu_info() return different value depends on which CPU it is 
> > running ?
>
> Yes.  The stack is per cpu and it returns a fixed address from
> the stack structure.

Why you push the cpu index and struct cpu in c_start.S ? Is it parameter
to the hardwaremain() ?

And why you save the %esp before init IDT and restore it ? I don't see
it is modified when init IDT.

BTW, I think c_start.S is only executed on BSP, right ?

Ollie

/* Push the cpu index and struct cpu */
    pushl	$0
    pushl	$0

/* push the boot_complete flag */
    pushl	%ebp

/* Save the stack location */
    movl	%esp, %ebp

/* Initialize the Interrupt Descriptor table */
    xxx
    xxx

/* Load the Interrupt descriptor table */
    lidt	idtarg

intel_chip_post_macro(0xfe)	/* post fe */

/* Restore the stack location */
    movl	%ebp, %esp
    
    /* The boot_complete flag has already been pushed */
    call	hardwaremain
    /*NOTREACHED*/