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

[John Williams]

On Mon, Jan 30, 2012 at 12:11 PM, Anthony Liguori <address@hidden> wrote:
> On 01/29/2012 06:28 PM, John Williams wrote:
>>
>> On Sun, Jan 29, 2012 at 4:51 PM, Peter Crosthwaite
>> <address@hidden>  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 address@hidden
>
>
> Make an elf loader device if you desire this ability but I'm skeptical that
> it really is all that useful.

It is useful for non-Linux use-cases, of which there are many!

Can you explain how you'd see such a 'loader device' in practice?  How
does it get bound into the machine model?  How do we pass arguments to
it?

Thanks,

John
-- 
John Williams, PhD, B. Eng, B. IT
PetaLogix - Linux Solutions for a Reconfigurable World
w: www.petalogix.com  p: +61-7-30090663  f: +61-7-30090663