Re: [Qemu-devel] [RFC PATCH 5/7] vl.c: added -kerndtb option

[Anthony Liguori <anthony@codemonkey.ws>]

On 01/29/2012 06:28 PM, John Williams wrote:
> On Sun, Jan 29, 2012 at 4:51 PM, Peter Crosthwaite
> <peter.crosthwaite@petalogix.com>  wrote:
>> Hi All,
>>
>> So on the topic of these command line arguments for initrd, dtb and friends,
>> another related issue we have encountered (and have hacked around in our
>> tree) is not being able to relocate the initrd or kernel. Currently these
>> memory locations are hardcoded in arm_boot.c:
>>
>> #define KERNEL_ARGS_ADDR 0x100
>> #define KERNEL_LOAD_ADDR 0x00010000
>> #define INITRD_LOAD_ADDR 0x00d00000
>>
>> If you see patch 6/7 in this same series I put in place a hack to override
>> the initrd location in memory, but I wonder if instead this should go up to
>> the command line interface as a parameter. Currently the machine model (or
>> arm_boot.c) defines exactly where kernels/initrds/command-line-args line in
>> memory, but since these are software properties should perhaps they go up to
>> the command line as -kernel,foo=bar options? E.G:
>>
>> qemu-system-arm
>> -kernel,kernel-image=/foo/zImage,kernel-addr=0x00010000,initrd=/foo/initrd,initrd_addr=0x00d00000
>
> There's an opportunity here - QEMU needs the cmdline ability to load
> random binaries/elfs anyway, such as
>
> --load file@address

Make an elf loader device if you desire this ability but I'm skeptical that it 
really is all that useful.

No special syntax though, we have a way to parameterize options as Markus 
rightly points out.

Regards,

Anthony Liguori

>
> e.g. --load image.bin@0xa4000000
>
> -- load file.elf
>
> (no address required)
>
> This option or one like it would make it much easier and less
> hard-coded to assemble any sort of initial memory state.
>
> Extending this, kernels, initrds and DTBs all can have
> machine-specific preferred addresses but can be overriden in the same
> way:
>
> --kernel zImage@0x20000000 --initrd fs.img@0x40000000
>
> and so on
>
> The '@' symbol will need to be escaped by it's a pretty natural syntax.
>
> John