On 04/07/23 07:57, Krzysztof Kozlowski wrote:

On 03/07/2023 17:55, Mukesh Ojha wrote:

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On 7/3/2023 12:50 PM, Krzysztof Kozlowski wrote:

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On Mon, 3 Jul 2023 at 08:22, Mukesh Ojha [off-list ref] wrote:

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On 7/2/2023 1:42 PM, Krzysztof Kozlowski wrote:

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The big difference is if firmware is not deciding where this log
lives, then it doesn't need to be in DT. How does anything except the
kernel that allocates the log find the logs?

Yes, you are correct, firmware is not deciding where the logs lives
instead here, Kernel has reserved the region where the ramoops region
lives and later with the minidump registration where, physical
address/size/virtual address(for parsing) are passed and that is how
firmware is able to know and dump those region before triggering system
reset.

Your explanation does not justify storing all this in DT. Kernel can
allocate any memory it wishes, store there logs and pass the address to
the firmware. That's it, no need for DT.

If you go through the driver, you will know that what it does, is

We talk about bindings and I should not be forced to look at the
driver to be able to understand them. Bindings should stand on their
own.

Why can't ramoops binding have one more feature where it can add a flag
*dynamic* to indicate the regions are dynamic and it is for platforms
where there is another entity 'minidump' who is interested in these
regions.

Because we do not define dynamic stuff in Devicetree. Dynamic means
defined by SW or runtime configurable. It is against the entire idea of
Devicetree which is for non-discoverable hardware.

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just create platform device for actual ramoops driver to probe and to

Not really justification for Devicetree anyway. Whatever your driver
is doing, is driver's business, not bindings.

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provide this it needs exact set of parameters of input what original
ramoops DT provides, we need to keep it in DT as maintaining this in
driver will not scale well with different size/parameter size
requirement for different targets.

Really? Why? I don't see a problem in scaling. At all.

I had attempted it here,

https://lore.kernel.org/lkml/1683133352-10046-10-git-send-email-quic_mojha@quicinc.com/ (local)

but got comments related to hard coding and some in favor of having
the same set of properties what ramoops has/provides

https://lore.kernel.org/lkml/e25723bf-be85-b458-a84c-1a45392683bb@gmail.com/ (local)

https://lore.kernel.org/lkml/202305161347.80204C1A0E@keescook/ (local)

Then you were tricked. I don't get why someone else suggests that
non-hardware property should be part of Devicetree, but anyway it's the
call of Devicetree binding maintainers, not someone else. DT is not
dumping ground for all the system configuration variables.

Sorry for that, I assumed the interface should be as close as possible 
to pstore, but apparently that's not the case. Why does it have to be 
different from it? It provides the same functionality and is 
configurable even if it doesn't explicitly configure non discoverable 
hardware properties.

Assuming we make the driver picks the values, how would it do that?  
Hardcoding a configuration could lead to a few problems, such as the 
allocated region being smaller than the driver defaults or driver 
defaults not fully utilizing the allocated region, possibly wasting more 
memory than it'll ever use. On top of that what happens if we want to 
configure it differently than the hardcoded default values? Via cmdline 
options? For example in the previous version it allocated the whole 
region for the console alone, while other entries, such as pmsg that 
could be useful on devices using minidump to store Android logs, was 
zero-sized.

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A part of this registration code you can find in 11/21

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I'm pretty sure I already said all this before.

Yes, you said this before but that's the reason i came up with vendor
ramoops instead of changing traditional ramoops binding.

That's unexpected conclusion. Adding more bindings is not the answer to
comment that it should not be in the DTS in the first place.

Please suggest, what is the other way being above text as requirement..

I do not see any requirement for us there. Forcing me to figure out
how to add non-hardware property to DT is not the way to convince
reviewers. But if you insist - we have ABI for this, called sysfs. If
it is debugging feature, then debugfs.

ramoops already support module params and a way to pass these parameters
from bootargs but it also need to know the hard-codes addresses, so,
doing something in sysfs will be again duplication with ramoops driver..

Why do you need hard-coded addresses?

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If this can be accommodated under ramoops, this will be very small
change, like this

https://lore.kernel.org/lkml/20230622005213.458236-1-isaacmanjarres@google.com/ (local)

That's also funny patch - missing bindings updated, missing CC DT
maintainers.

Best regards,
Krzysztof

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