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Date:   Thu, 25 May 2023 14:37:43 +0100
From:   Conor Dooley <conor.dooley@microchip.com>
To:     Anup Patel <apatel@ventanamicro.com>
CC:     Atish Patra <atishp@atishpatra.org>,
        Alexandre Ghiti <alex@ghiti.fr>, <robh@kernel.org>,
        Alexandre Ghiti <alexghiti@rivosinc.com>,
        <jeeheng.sia@starfivetech.com>, Anup Patel <anup@brainfault.org>,
        <linux-kernel@vger.kernel.org>, <palmer@rivosinc.com>,
        <leyfoon.tan@starfivetech.com>, <mason.huo@starfivetech.com>,
        Guo Ren <guoren@kernel.org>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Song Shuai <suagrfillet@gmail.com>,
        <linux-riscv@lists.infradead.org>,
        Andrew Jones <ajones@ventanamicro.com>
Subject: Re: Bug report: kernel paniced when system hibernates
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On Thu, May 25, 2023 at 06:51:28PM +0530, Anup Patel wrote:

> > We should only rely on this node name for known bad versions of opensbi
> > IMO. Going forward, if something needs to be reserved for firmware, the
> > firmware should make sure that it is reserved by using the property for
> > that purpose :)

> There is no issue with OpenSBI since it does the right thing by marking
> memory as reserved in the DT. This real issue is with the kernel handling
> of reserved memory for hibernate.

I don't think we are talking about the same thing here. I meant the
no-map property which OpenSBI does not set.

> Like Atish mentioned, not just OpenSBI, there will be other entities
> (like TSM) or some other M-mode firmware which will also reserve
> memory in DT/ACPI so clearly kernel needs a SBI implementation
> independent way of handling reserved memory for hibernate.

> > > Another option is to use compatible string or label property to indicate
> > > that this memory region is not to be saved/restored during hibernation.
> > > This can be documented in RISC-V DT bindings as well as the booting guide
> > > doc that alex was talking about.
> >
> > Sure, a dt-binding for sbi reserved regions doesn't immediately sound
> > like an awful idea... But we still have to work around the borked
> > firmware - be that disabling hibernation or using the mmode_resv node
> > when we know that the version of OpenSBI is one of those with the
> > problem.

Did you skip over this? I was agreeing that defining a common binding for
sbi reserved regions was a good idea.

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