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Date: Tue, 2 Jan 2024 07:53:17 -0700
From: Rob Herring <robh@kernel.org>
To: Alexander Graf <graf@amazon.com>
Cc: Krzysztof Kozlowski <krzk@kernel.org>, linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-mm@kvack.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kexec@lists.infradead.org, linux-doc@vger.kernel.org, x86@kernel.org, Eric Biederman <ebiederm@xmission.com>, "H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Steven Rostedt <rostedt@goodmis.org>, Andrew Morton <akpm@linux-foundation.org>, Mark Rutland <mark.rutland@arm.com>, Tom Lendacky <thomas.lendacky@amd.com>, Ashish Kalra <ashish.kalra@amd.com>, James Gowans <jgowans@amazon.com>, Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>, arnd@arndb.de, pbonzini@redhat.com, madvenka@linux.microsoft.com, Anthony Yznaga <anthony.yznaga@oracle.com>, Usama Arif <usama.arif@bytedance.com>, David Woodhouse <dwmw@amazon.co.uk>, Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH v2 17/17] devicetree: Add bindings for ftrace KHO
Message-ID: <20240102145317.GA2815776-robh@kernel.org>
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In-Reply-To: <34e78a84-a29d-4b01-a860-cac3959f6cb6@amazon.com>

On Sun, Dec 24, 2023 at 12:20:17AM +0100, Alexander Graf wrote:
> Hi Krzysztof!
> 
> Thanks a lot for the fast review!
> 
> On 23.12.23 15:30, Krzysztof Kozlowski wrote:
> > On 22/12/2023 20:51, Alexander Graf wrote:
> > > With ftrace in KHO, we are creating an ABI between old kernel and new
> > > kernel about the state that they transfer. To ensure that we document
> > > that state and catch any breaking change, let's add its schema to the
> > > common devicetree bindings. This way, we can quickly reason about the
> > > state that gets passed.
> > Please use scripts/get_maintainers.pl to get a list of necessary people
> > and lists to CC (and consider --no-git-fallback argument). It might
> > happen, that command when run on an older kernel, gives you outdated
> > entries. Therefore please be sure you base your patches on recent Linux
> > kernel.

[...]

> > 
> > > +            mem = < 0x101000000ULL 0x38ULL 0x101000100ULL 0x1000ULL 0x101000038ULL 0x38ULL 0x101002000ULL 0x1000ULL>;
> > ? Do you see any of such syntax in DTS?
> 
> 
> I was trying to make it easy to reason to readers about 64bit numbers - and
> then potentially extend dtc to consume that new syntax. KHO DTs are
> native/little endian, so dtc already has some difficulties interpreting it
> which I'll need to fix up with patches to it eventually :). I'll change it
> to something that looks more 32bit'y for now.

"/bits/ 64 <0x0 ...>" is what you are looking for.

Rob