On 11.12.2007 05:43, ron minnich wrote:
> note that the stage1_main code calls disable_car, then stage1_next.
> But disable_car calls stage1_next too! how
> can this works?
>
> The redundant call ensures this code works no
> matter whether the chip-dependent disable_car calls stage1_next or not.
>
I don't like this. disable_car() should just be able to return without
problems. If it can't do that, fix it.
Otherwise we have to document the call to stage1_end() as a requirement
of any diable_car() function and *justify* it.
> This change makes it possible for an lx to get through CAR to stage2.
>
> It's kind of ugly, but what it does is require the CAR code to call
> a function, stage1_end. Why might this be needed? Because, at the end
> of CAR, we invalidate the stack, which in turn *on some systems* will lose
> the return address. We are thus losing our stack in disable_car, and
> to compensate, we are jumping.
>
Why exactly do we invalidate the stack? If the stack is clobbered, the
contents of variables should be in a clobbered state as well. In that
case, I suspect parts of our v3 code would misbehave as well.
Can we make sure the stack contents are preserved?
> Signed-off-by: Ronald G. Minnich <[EMAIL PROTECTED]>
>
> Index: arch/x86/stage1.c
> ===================================================================
> --- arch/x86/stage1.c (revision 542)
> +++ arch/x86/stage1.c (working copy)
> @@ -73,23 +73,12 @@
> */
> void __attribute__((stdcall)) stage1_main(u32 bist)
> {
> + void stage1_end(void);
> int ret;
> - struct mem_file archive, result;
> + struct mem_file archive;
> int elfboot_mem(struct lb_memory *mem, void *where, int size);
> - void *entry;
>
> - /* we can't statically init this hack. */
> - unsigned char faker[64];
> - struct lb_memory *mem = (struct lb_memory*) faker;
>
> - mem->tag = LB_TAG_MEMORY;
> - mem->size = 28;
> - mem->map[0].start.lo = mem->map[0].start.hi = 0;
> - mem->map[0].size.lo = (32*1024*1024);
> - mem->map[0].size.hi = 0;
> - mem->map[0].type = LB_MEM_RAM;
> -
> -
> post_code(0x02);
>
> // before we do anything, we want to stop if we dont run
> @@ -159,7 +148,27 @@
>
> /* Turn off Cache-As-Ram */
> disable_car();
> + stage1_end();
> +}
>
> +void stage1_end(void)
> +{
> + int ret;
> + struct mem_file archive, result;
> + int elfboot_mem(struct lb_memory *mem, void *where, int size);
> + void *entry;
> + /* we can't statically init this hack. */
> + unsigned char faker[64];
> + struct lb_memory *mem = (struct lb_memory*) faker;
> +
> + mem->tag = LB_TAG_MEMORY;
> + mem->size = 28;
> + mem->map[0].start.lo = mem->map[0].start.hi = 0;
> + mem->map[0].size.lo = (32*1024*1024);
> + mem->map[0].size.hi = 0;
> + mem->map[0].type = LB_MEM_RAM;
> +
> +
> entry = load_file_segments(&archive, "normal/stage2");
> if (entry == (void *)-1)
> die("FATAL: Failed loading stage2.");
> Index: arch/x86/geodelx/stage1.c
> ===================================================================
> --- arch/x86/geodelx/stage1.c (revision 542)
> +++ arch/x86/geodelx/stage1.c (working copy)
> @@ -55,9 +55,11 @@
> void disable_car(void)
> {
> int i;
> + void stage1_end(void);
>
If we really want to call stage1_end from disable_car(), we have to move
that to a header file.
>
> for (i = 0; i < ARRAY_SIZE(msr_table); i++)
> wrmsr(msr_table[i].msrnum, msr_table[i].msr);
>
> __asm__("wbinvd\n");
> + stage1_end();
>
Disagreed, se above.
> }
Carl-Daniel
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