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Re: [Qemu-devel] [PATCH v7 3/3] docs: Add a generic loader explanation d


From: Alistair Francis
Subject: Re: [Qemu-devel] [PATCH v7 3/3] docs: Add a generic loader explanation document
Date: Mon, 13 Jun 2016 13:17:47 -0700

On Mon, Jun 13, 2016 at 10:49 AM, Peter Maydell
<address@hidden> wrote:
> On 13 June 2016 at 18:45, Alistair Francis <address@hidden> wrote:
>> On Thu, Jun 9, 2016 at 10:45 AM, Peter Maydell <address@hidden> wrote:
>>> On 25 May 2016 at 19:49, Alistair Francis <address@hidden> wrote:
>>>> Signed-off-by: Alistair Francis <address@hidden>
>>>> ---
>>>> V6:
>>>>  - Fixup documentation
>>>> V4:
>>>>  - Re-write to be more comprehensive
>>>>
>>>>  docs/generic-loader.txt | 54 
>>>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>>>  1 file changed, 54 insertions(+)
>>>>  create mode 100644 docs/generic-loader.txt
>>>>
>>>> diff --git a/docs/generic-loader.txt b/docs/generic-loader.txt
>>>> new file mode 100644
>>>> index 0000000..effb244
>>>> --- /dev/null
>>>> +++ b/docs/generic-loader.txt
>>>> @@ -0,0 +1,54 @@
>>>> +Copyright (c) 2016 Xilinx Inc.
>>>> +
>>>> +This work is licensed under the terms of the GNU GPL, version 2 or later. 
>>>>  See
>>>> +the COPYING file in the top-level directory.
>>>> +
>>>> +
>>>> +The 'loader' device allows the user to load multiple images or values into
>>>> +QEMU at startup.
>>>> +
>>>> +Loading Memory Values
>>>> +---------------------
>>>> +The loader device allows memory values to be set from the command line. 
>>>> This
>>>> +can be done by following the syntax below:
>>>> +
>>>> +    -device loader,addr=<addr>,data=<data>,data-len=<len>
>>>> +    -device loader,addr=<addr>,cpu-num=<cpu-num>
>>>> +
>>>> +NOTE: It is also possible to mix the commands above, e.g. include the 
>>>> cpu-num
>>>> +      argument with the data argument.
>>>
>>> Is that actually useful?
>>
>> Sometimes it is. You can use it to set data in other CPU address spaces.
>
> Right, but do you want it to do that and also set the PC of the other CPU
> at the same time? That's the bit that doesn't make sense to me.
> I think we should keep "set PC" and "write to memory" orthogonal,
> rather having an option combo that does both on the same data.
>
>> It also is not forbidden in all the checks, so I think it is still
>> worth mentioning.
>
> Better to forbid combinations that don't make sense rather than document them.

Ok, I have done that.

>
>>> Does this also cause the loader to write via this CPU's address space?
>>
>> The file loading does not follow the CPUs address spaces. It only sets
>> the CPUs program counter.
>>
>> The <data> writes follow the CPUs address spaces though.
>
> That's irritatingly inconsistent. Can we have both use the CPU's
> address space, please?

I don't see an easy way to set the address space for the multiple
loader functions. Any ideas?

Thanks,

Alistair

>
> thanks
> -- PMM
>



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