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From:   David Abdurachmanov <david.abdurachmanov@gmail.com>
Date:   Mon, 7 Feb 2022 10:05:14 +0200
Message-ID: <CAEn-LTrZwq1-6F8PWScGPp1TRk1eaB-7qOrvPjyLhK=OzDTQBQ@mail.gmail.com>
Subject: Re: [RFC PATCH] riscv: reduce THREAD_SIZE from 16KB to 8KB for RV64
To:     Jisheng Zhang <jszhang@kernel.org>
Cc:     Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        linux-riscv <linux-riscv@lists.infradead.org>,
        "linux-kernel@vger.kernel.org List" <linux-kernel@vger.kernel.org>
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On Sun, Feb 6, 2022 at 7:53 PM Jisheng Zhang <jszhang@kernel.org> wrote:
>
> After irq stack is supported, it's possible to use small THREAD_SIZE.
> In fact, I tested this patch on a Lichee RV board, looks good so far.

We went from 8K to 16K somewhere in mid-2020 on riscv64 because we
were seeing some random crashes in various distributions (Debian,
Fedora, OpenSUSE). Thus we matched what other popular arches do, i.e.
16K.

Thus I would be very careful going back to 8K.

david

>
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  arch/riscv/include/asm/thread_info.h | 4 ----
>  1 file changed, 4 deletions(-)
>
> diff --git a/arch/riscv/include/asm/thread_info.h b/arch/riscv/include/asm/thread_info.h
> index 67387a8bcb34..fdbf3890a1ab 100644
> --- a/arch/riscv/include/asm/thread_info.h
> +++ b/arch/riscv/include/asm/thread_info.h
> @@ -12,11 +12,7 @@
>  #include <linux/const.h>
>
>  /* thread information allocation */
> -#ifdef CONFIG_64BIT
> -#define THREAD_SIZE_ORDER      (2)
> -#else
>  #define THREAD_SIZE_ORDER      (1)
> -#endif
>  #define THREAD_SIZE            (PAGE_SIZE << THREAD_SIZE_ORDER)
>
>  #define IRQ_STACK_SIZE         THREAD_SIZE
> --
> 2.34.1
>
>
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