Re: aout support almost working now

[walt <wa1ter@myrealbox.com>]

Bean wrote:
> On Feb 7, 2008 3:23 AM, walt<wa1ter@myrealbox.com>  wrote:
>> With Bean's last two commits I can almost replace legacy with grub2
>> at least on x86.  I have still one problem with the aout support that
>> Bean posted as a patch on Jan 27.
>>
>> Using legacy, which loads the FreeBSD /boot/loader as the 'kernel',
>> loader then reads its config files from the /boot directory so it
>> knows what parameters to pass to the real kernel and also what menu
>> items to show the user.
>>
>> Using grub2 with Bean's aout patch,  I can load /boot/loader and
>> then boot it successfully, but it seems that 'loader' can't find
>> its config files in the /boot directory.  This is what it prints:
>>
>> Can't work out which disk we are booting from.
>> Guessed BIOS device 0xffffffff not found by probes,
>> defaulting to disk0:  can't load "kernel".
>>
>> At least on my machine, disk0 is the floppy drive and loader does
>> actually go to try to read it before printing the error messages
>> I listed, and then it drops to its interactive prompt.
>>
>> By examining the loader's variables it's clear that it never found
>> its usual config files in /boot.
>>
>> BTW, I did set 'root' and 'prefix' to point at the correct partition
>> before booting the loader.
>>
>> Any ideas what else to try?
>
> i think the %edx should be set before jumping to code, try this patch:
>
> diff --git a/kern/i386/loader.S b/kern/i386/loader.S
> index 266f4ef..88f3045 100644
> --- a/kern/i386/loader.S
> +++ b/kern/i386/loader.S
> @@ -137,6 +137,7 @@ FUNCTION(grub_multiboot_real_boot)
>   	cli
>   	
>   	/* Move the magic value into eax and jump to the kernel.  */
> +	movl	$0x80, %edx
>   	movl	$MULTIBOOT_MAGIC2,%eax
>   	popl	%ecx
>   	jmp 	*%ecx
> @@ -159,6 +160,7 @@ FUNCTION(grub_multiboot2_real_boot)
>           cli
>
>           /* Move the magic value into eax and jump to the kernel.  */
> +	movl	$0x80, %edx
>           movl    $MULTIBOOT2_BOOTLOADER_MAGIC,%eax
>           popl    %ecx
>           jmp     *%ecx
>
> Please note that this is not a proper patch, it assume booting from
> the (hd0,0,a). you can adjust the value of %edx if you boot from other
> partition.

Sorry, I don't know what adjustment to make.  I did find a macro for
MULTIBOOT_INFO_DISK_INFO but it's never actually used anywhere :o/

I'm trying to load (hd0,3,a) -- can you show me the right value for %edx ?

Thanks.