linux-kernel - Re: [PATCH v2 07/19] remoteproc: Add new resource type for resource table spare bytes

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Message-ID: <c6b1b933-6cf5-55eb-5391-33e520205b34@st.com>
Date:   Mon, 19 Sep 2016 09:50:37 +0200
From:   loic pallardy <loic.pallardy@...com>
To:     Bjorn Andersson <bjorn.andersson@...aro.org>
CC:     <ohad@...ery.com>, <lee.jones@...aro.org>,
        <linux-remoteproc@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <kernel@...inux.com>
Subject: Re: [PATCH v2 07/19] remoteproc: Add new resource type for resource
 table spare bytes



On 09/16/2016 07:12 PM, Bjorn Andersson wrote:
> On Fri 16 Sep 02:02 PDT 2016, loic pallardy wrote:
>
>>
>>
>> On 09/15/2016 07:54 PM, Bjorn Andersson wrote:
>>> On Wed 31 Aug 13:50 PDT 2016, Loic Pallardy wrote:
>>>
>>>> To allow resource appending to an existing resource table,
>>>> remoteproc framework should get information about resource
>>>> table spare area. With current resource table construction,
>>>> remoteproc is not able to identify by itself any free location.
>>>> This patch introduces a new resource type named RSC_SPARE which
>>>> allows firmware to define room for resource table extension.
>>>> Defined spare area will be used by remtoreproc to extend resource
>>>> table.
>>>>
>>>
>>> We don't need a dummy type for keeping track of the available room in
>>> the resource table in the loaded firmware. All we need to do is to look
>>> at the sh_size of the .resource_table section, which actually is what's
>>> returned in tablesz.
>>>
>> This is the size of the .resource_table section. Doesn't means that only
>> resource table is stored in.
>
> I'm not sure I'm getting the details of what you're saying here. Do you
> mean that there could be other things in the resource_table section or
> just the fact that it being a section doesn't give any information about
> how much space this thing will have in loaded form.
>
>> Today this is the assumption and we force firmware to respect this.
>>
>
> I find it unfortunate that this was put in section and that we just have
> to make assumptions on how this projects onto the loaded form.
>
>>> So the spare size is the difference between tablesz and the end of the
>>> last resource and if you need you can pad this when composing the
>>> firmware.
>>>
>> Proposal was to clearly identify the area for extension (whatever
>> .resource_table section is done). But if you agree on the fact
>> .resource_tabel section constains only resource table and eventualy room for
>> extension, I can indeed simply room detection.
>>
>
> Could you describe your use case for programmatically generate a
> resource table for a firmware without a .resource_table? I would like to
> understand the contract between the driver and the firmware when it
> comes to what should go into the resource table.

No I always consider .resource_table section.
You answer to my point just above. .resource_table section must contain 
only the resource table and nothing else. I'm fine with that.

I'll revert RSC_SPARE type.

Regards,
Loic
>
> Regards,
> Bjorn
>