Re: [Qemu-devel] [PATCH] Fix -kernel on target-ppc

[Alexander Graf]

On 24.01.2009, at 22:48, Aurelien Jarno wrote:

> On Sat, Jan 24, 2009 at 09:58:35PM +0100, Alexander Graf wrote:
> > OpenBIOS searches for the preloaded kernel at 0x1000000, so let's
> > put it there instead of an invalid location.
>
> Your patch is actually wrong, the second argument of load_elf() is an
> offset to the physical address (as found in the elf header), and not a
> load address.
>
> By chance the physical address of a >= 2.6.25 kernel is 0x00000000, so
> your patch works. But it will break supports for < 2.6.25 kernel as
> their physical address is 0xc0000000. Not that they are only the  
> default
> values, they can be changed in the .config file.

Aah, that explains why :-).

> I have already proposed a patch to use the virtual address of the elf
> header as done by yaboot or quik, but I have been told it is actually
> wrong.
>
> We have to find another way to load the elf file at a fixed address.

Hm - can't we just give load_elf an override value for the base address?

            /* address_offset is hack for kernel images that are
               linked at the wrong physical address.  */
            addr = ph->p_paddr + address_offset;

            cpu_physical_memory_write_rom(addr, data, mem_size);

Just pass another variable here that overrides addr and doesn't  
calculate it?

Alex

> > Using this patch I was able to use -kernel for a current openSUSE
> > 11.1 kernel.
> >
> > Signed-off-by: Alexander Graf <address@hidden>
> > ---
> > hw/ppc_oldworld.c |    2 +-
> > 1 files changed, 1 insertions(+), 1 deletions(-)
> >
> > diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
> > index 042a40f..0af2436 100644
> > --- a/hw/ppc_oldworld.c
> > +++ b/hw/ppc_oldworld.c
> > @@ -209,7 +209,7 @@ static void ppc_heathrow_init (ram_addr_t  
> > ram_size, int vga_ram_size,
> >     if (linux_boot) {
> >         kernel_base = KERNEL_LOAD_ADDR;
> >         /* now we can load the kernel */
> > -        kernel_size = load_elf(kernel_filename, kernel_base -  
> > 0xc0000000ULL,
> > +        kernel_size = load_elf(kernel_filename, KERNEL_LOAD_ADDR,
> >                                NULL, NULL, NULL);
> >         if (kernel_size < 0)
> >             kernel_size = load_aout(kernel_filename, kernel_base,
> > --
> > 1.6.0.2
>
> --
> Aurelien Jarno                          GPG: 1024D/F1BCDB73
> address@hidden                 http://www.aurel32.net