Re: [Qemu-devel] [PATCH] Always load PowerPC kernel to KERNEL_LOAD_ADDR

[Edgar E. Iglesias]

On Sun, Jan 25, 2009 at 12:54:27PM +0100, Alexander Graf wrote:
> Linux changed its physical address location in the elf header from
> 0xc0000000 to 0 on 2.6.25, causing later kernels to fail booting
> with the -kernel option.
> 
> This patch assures that the lowest segment in the elf binary is loaded
> to KERNEL_LOAD_ADDR, which is where the firmware expects it.
> 
> With this patch applied, I was able to successfully boot a 2.6.18 and
> a 2.6.27 Linux kernel using the -kernel option.
> 
> Signed-off-by: Alexander Graf <address@hidden>
> ---
>  hw/ppc_oldworld.c |    4 +++-
>  1 files changed, 3 insertions(+), 1 deletions(-)
> 
> diff --git a/hw/ppc_oldworld.c b/hw/ppc_oldworld.c
> index 042a40f..f64884b 100644
> --- a/hw/ppc_oldworld.c
> +++ b/hw/ppc_oldworld.c
> @@ -207,9 +207,11 @@ static void ppc_heathrow_init (ram_addr_t ram_size, int 
> vga_ram_size,
>      }
>  
>      if (linux_boot) {
> +        uint64_t lowaddr = 0;
>          kernel_base = KERNEL_LOAD_ADDR;
>          /* now we can load the kernel */
> -        kernel_size = load_elf(kernel_filename, kernel_base - 0xc0000000ULL,
> +        load_elf(kernel_filename, 0, NULL, &lowaddr, NULL);
> +        kernel_size = load_elf(kernel_filename, kernel_base - lowaddr,
>                                 NULL, NULL, NULL);

Hello,

Can't you speculatively load at kernel_base assuming it's a new kernel,
then only if lowaddr indicates it was an old kernel you do the second
load to fix things up?

Maybe also a comment or two in the code explaining the hack.. :)

Cheers