linux-kernel - Re: [PATCH] arch/riscv: disable too many harts before pick main boot hart

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Date:   Thu, 19 Sep 2019 10:30:15 +0000
From:   Xiang Wang <merle@...denedlinux.org>
To:     Paul Walmsley <paul.walmsley@...ive.com>
Cc:     "palmer@...ive.com" <palmer@...ive.com>,
        "aou@...s.berkeley.edu" <aou@...s.berkeley.edu>,
        "linux-riscv@...ts.infradead.org" <linux-riscv@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "citypw@...denedlinux.org" <citypw@...denedlinux.org>
Subject: Re: [PATCH] arch/riscv: disable too many harts before pick main boot hart






‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On 2019年9月19日ThursdayPM6点25分, Paul Walmsley <paul.walmsley@...ive.com> wrote:

> On Fri, 6 Sep 2019, Xiang Wang wrote:
>
> > From 12300865d1103618c9d4c375f7d7fbe601b6618c Mon Sep 17 00:00:00 2001
> > From: Xiang Wang merle@...denedlinux.org
> > Date: Fri, 6 Sep 2019 11:56:09 +0800
> > Subject: [PATCH] arch/riscv: disable too many harts before pick main boot hart
> > These harts with id greater than or equal to CONFIG_NR_CPUS need to be disabled.
> > But pick the main Hart can choose any one. So, before pick the main hart, you
> > need to disable the hart with id greater than or equal to CONFIG_NR_CPUS.
> > Signed-off-by: Xiang Wang merle@...denedlinux.org
>
> Thanks, here's what I'm planning to queue for v5.4-rc1. Please let me
> know ASAP if you want to change the patch description.
>
> -   Paul

Not need to change

>
>     From: Xiang Wang merle@...denedlinux.org
>
>
> Date: Fri, 6 Sep 2019 11:56:09 +0800
> Subject: [PATCH] arch/riscv: disable excess harts before picking main boot hart
>
> Harts with id greater than or equal to CONFIG_NR_CPUS need to be
> disabled. But the kernel can pick any hart as the main hart. So,
> before picking the main hart, the kernel must disable harts with ids
> greater than or equal to CONFIG_NR_CPUS.
>
> Signed-off-by: Xiang Wang merle@...denedlinux.org
> Reviewed-by: Palmer Dabbelt palmer@...ive.com
> [paul.walmsley@...ive.com: updated to apply; cleaned up patch
> description]
> Signed-off-by: Paul Walmsley paul.walmsley@...ive.com
>
> arch/riscv/kernel/head.S | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S
> index 15a9189f91ad..72f89b7590dd 100644
> --- a/arch/riscv/kernel/head.S
> +++ b/arch/riscv/kernel/head.S
> @@ -63,6 +63,11 @@ _start_kernel:
> li t0, SR_FS
> csrc CSR_SSTATUS, t0
>
> +#ifdef CONFIG_SMP
>
> -   li t0, CONFIG_NR_CPUS
> -   bgeu a0, t0, .Lsecondary_park
>     +#endif
>
> -   /* Pick one hart to run the main boot sequence */
>     la a3, hart_lottery
>     li a2, 1
>     @@ -154,9 +159,6 @@ relocate:
>
>     .Lsecondary_start:
>     #ifdef CONFIG_SMP
>
>
> -   li a1, CONFIG_NR_CPUS
> -   bgeu a0, a1, .Lsecondary_park
> -   /* Set trap vector to spin forever to help debug */
>     la a3, .Lsecondary_park
>     csrw CSR_STVEC, a3
>     --
>     2.23.0
>