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From:   Anup Patel <anup@brainfault.org>
Date:   Sat, 15 Feb 2020 19:10:57 +0530
Message-ID: <CAAhSdy0LQ7ov0Gm0ATxrmJuyKpjjn5e9iAxMPJLCVXA9Pdduqw@mail.gmail.com>
Subject: Re: [PATCH v2 1/3] riscv: Add support for mem=
To:     Jan Kiszka <jan.kiszka@web.de>
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 Sat, Feb 15, 2020 at 5:20 PM Jan Kiszka <jan.kiszka@web.de> wrote:
>
> From: Jan Kiszka <jan.kiszka@siemens.com>
>
> This sets a memory limit provided via mem= on the command line,
> analogously to many other architectures.
>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
>  arch/riscv/mm/init.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
>
> diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
> index 965a8cf4829c..aec39a56d6cf 100644
> --- a/arch/riscv/mm/init.c
> +++ b/arch/riscv/mm/init.c
> @@ -118,6 +118,23 @@ static void __init setup_initrd(void)
>  }
>  #endif /* CONFIG_BLK_DEV_INITRD */
>
> +static phys_addr_t memory_limit = PHYS_ADDR_MAX;
> +
> +/*
> + * Limit the memory size that was specified via FDT.
> + */
> +static int __init early_mem(char *p)
> +{
> +       if (!p)
> +               return 1;
> +
> +       memory_limit = memparse(p, &p) & PAGE_MASK;
> +       pr_notice("Memory limited to %lldMB\n", memory_limit >> 20);
> +
> +       return 0;
> +}
> +early_param("mem", early_mem);
> +
>  static phys_addr_t dtb_early_pa __initdata;
>
>  void __init setup_bootmem(void)
> @@ -127,6 +144,8 @@ void __init setup_bootmem(void)
>         phys_addr_t vmlinux_end = __pa_symbol(&_end);
>         phys_addr_t vmlinux_start = __pa_symbol(&_start);
>
> +       memblock_enforce_memory_limit(memory_limit);
> +
>         /* Find the memory region containing the kernel */
>         for_each_memblock(memory, reg) {
>                 phys_addr_t end = reg->base + reg->size;
> --
> 2.16.4
>
>

This is a good addition for Linux RISC-V.

Looks good to me.

Reviewed-by: Anup Patel <anup@brainfault.org>

Regards,
Anup