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Message-ID: <6fee29f8-8150-e6ec-e2ec-210610a7e27d@ghiti.fr>
Date:   Fri, 25 Nov 2022 14:41:11 +0100
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Subject: Re: [PATCH] riscv: increase boot command line size to 1K
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To:     Andrea Righi <andrea.righi@canonical.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>
Cc:     Emil Renner Berthing <emil.renner.berthing@canonical.com>,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20221125133713.314796-1-andrea.righi@canonical.com>
From:   Alexandre Ghiti <alex@ghiti.fr>
In-Reply-To: <20221125133713.314796-1-andrea.righi@canonical.com>
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Hi Andrea,

On 11/25/22 14:37, Andrea Righi wrote:
> Kernel parameters string is limited to 512 characters on riscv (using
> the default from include/uapi/asm-generic/setup.h).
>
> In some testing environments (e.g., qemu with long kernel parameters
> string) we may exceed this limit, triggering errors like the following:
>
> [    3.331893] Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000
> [    3.332625] CPU: 2 PID: 1 Comm: sh Not tainted 6.1.0-rc6-kc #1
> [    3.333233] Hardware name: riscv-virtio,qemu (DT)
> [    3.333550] Call Trace:
> [    3.333736] [<ffffffff800062b6>] dump_backtrace+0x1c/0x24
> [    3.334053] [<ffffffff806e8f54>] show_stack+0x2c/0x38
> [    3.334260] [<ffffffff806f2d06>] dump_stack_lvl+0x5a/0x7c
> [    3.334483] [<ffffffff806f2d3c>] dump_stack+0x14/0x1c
> [    3.334687] [<ffffffff806e92fa>] panic+0x116/0x2d0
> [    3.334878] [<ffffffff8001b0aa>] do_exit+0x80a/0x810
> [    3.335079] [<ffffffff8001b1d0>] do_group_exit+0x24/0x70
> [    3.335287] [<ffffffff8001b234>] __wake_up_parent+0x0/0x20
> [    3.335502] [<ffffffff80003cee>] ret_from_syscall+0x0/0x2
> [    3.335857] SMP: stopping secondary CPUs
> [    3.337561] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000000 ]---
>
> It seems reasonable enough to increase the default command line size to
> 1024, like arm, to prevent issues like the one reported above.
>
> Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
> ---
>   arch/riscv/include/asm/setup.h      | 7 +++++++
>   arch/riscv/include/uapi/asm/setup.h | 7 +++++++
>   2 files changed, 14 insertions(+)
>   create mode 100644 arch/riscv/include/asm/setup.h
>   create mode 100644 arch/riscv/include/uapi/asm/setup.h
>
> diff --git a/arch/riscv/include/asm/setup.h b/arch/riscv/include/asm/setup.h
> new file mode 100644
> index 000000000000..f4fe549aab40
> --- /dev/null
> +++ b/arch/riscv/include/asm/setup.h
> @@ -0,0 +1,7 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +#ifndef __ASMRISCV_SETUP_H
> +#define __ASMRISCV_SETUP_H
> +
> +#include <uapi/asm/setup.h>
> +
> +#endif /* __ASMRISCV_SETUP_H */
> diff --git a/arch/riscv/include/uapi/asm/setup.h b/arch/riscv/include/uapi/asm/setup.h
> new file mode 100644
> index 000000000000..5738f93ae437
> --- /dev/null
> +++ b/arch/riscv/include/uapi/asm/setup.h
> @@ -0,0 +1,7 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _UAPI__ASMRISCV_SETUP_H
> +#define _UAPI__ASMRISCV_SETUP_H
> +
> +#define COMMAND_LINE_SIZE 1024
> +
> +#endif /* _UAPI__ASMRISCV_SETUP_H */


Just for reference to previous discussions regarding this: 
https://lore.kernel.org/lkml/CACT4Y+YYAfTafFk7DE0B=qQFgkPXS7492AhBdY_CP1WdB8CGfA@mail.gmail.com/T/

Thanks,

Alex