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From: Sunil V L <sunilvl@ventanamicro.com>
To: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	Atish Patra <atishp@atishpatra.org>,
	Abner Chang <abner.chang@hpe.com>,
	Jessica Clarke <jrtc27@jrtc27.com>,
	Anup Patel <anup@brainfault.org>,
	Palmer Dabbelt <palmer@rivosinc.com>
Cc: sunil.vl@gmail.com, linux-riscv@lists.infradead.org
Subject: Question regarding "boot-hartid" DT node
Date: Thu, 2 Dec 2021 20:35:15 +0530	[thread overview]
Message-ID: <20211202150515.GA97518@sunil-ThinkPad-T490> (raw)

Hi All,
   I am starting this thread to discuss about the "boot-hartid" DT node
   that is being used in RISC-V Linux EFI stub.

   As you know, the boot Hart ID is passed in a0 register to the kernel
   and hence there is actually no need to pass it via DT. However, since
   EFI stub follows EFI application calling conventions, it needs to
   know the boot Hart ID so that it can pass it to the proper kernel via
   a0. For this issue, the solution was to add "/chosen/boot-hartid" in
   DT. Both EDK2 and u-boot append this node in DT.

   But above approach causes issue for ACPI since ACPI initialization
   happens late in the proper kernel. Same is true even if we pass this
   information via SMBIOS.

   Do you have any suggestions what can be done in ACPI case? Can we use
   a UEFI variable with RVI specific GUID to pass this information? This
   will have the advantage that it can work with either DT or ACPI.
   Also, we may not need any UEFI spec update. Do you see any issue with
   this approach? Your inputs will be very helpful.

Thanks!
Sunil

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             reply	other threads:[~2021-12-02 15:05 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-12-02 15:05 Sunil V L [this message]
2021-12-02 15:09 ` Question regarding "boot-hartid" DT node Heinrich Schuchardt
2021-12-02 15:17   ` Sunil V L
2021-12-02 15:52     ` Heinrich Schuchardt
2021-12-02 16:20 ` Ard Biesheuvel
2021-12-02 16:53   ` Heinrich Schuchardt
2021-12-02 16:58     ` Ard Biesheuvel
2021-12-02 17:04       ` Heinrich Schuchardt
2021-12-02 17:10         ` Ard Biesheuvel
2021-12-02 19:29         ` Atish Patra
2021-12-03 10:13           ` Ard Biesheuvel
2021-12-03 10:53             ` Heinrich Schuchardt
2021-12-03 18:45               ` Heinrich Schuchardt
2021-12-04  0:44                 ` Atish Patra
2021-12-04  1:47                   ` Heinrich Schuchardt
2021-12-04  4:24                     ` Anup Patel
2021-12-04  8:38                       ` Heinrich Schuchardt
2021-12-04 14:00                         ` Anup Patel
2021-12-04 18:34                       ` Atish Patra
2021-12-04 19:03                         ` Heinrich Schuchardt
2021-12-04 19:13                           ` Ard Biesheuvel
2022-01-13  9:44                             ` Sunil V L
2022-01-13  9:50                               ` Ard Biesheuvel
2022-01-13  9:59                                 ` Sunil V L
2022-01-13 10:01                                   ` Ard Biesheuvel
2022-01-18  4:47                                     ` Sunil V L
2021-12-05 13:39                         ` Sunil V L
2021-12-05 15:54                           ` Jessica Clarke
2021-12-05 16:37                             ` Sunil V L
     [not found]                               ` <CAOnJCUJ1jmwj4jrWsL2UnV8Wit_-w2KVnqUxy3gsvzE4ZugHBQ@mail.gmail.com>
2021-12-06  4:26                                 ` Sunil V L

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