linux-kernel - Re: [PATCH v9 5/8] x86/boot: Add get_acpi_rsdp() to parse RSDP in cmdlien from kexec

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Message-ID: <20181021022650.GI1885@192.168.1.4>
Date:   Sun, 21 Oct 2018 10:26:50 +0800
From:   Baoquan He <bhe@...hat.com>
To:     Chao Fan <fanc.fnst@...fujitsu.com>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        linux-efi@...r.kernel.org, linux-acpi@...r.kernel.org,
        bp@...en8.de, tglx@...utronix.de, mingo@...hat.com, hpa@...or.com,
        keescook@...omium.org, msys.mizuma@...il.com,
        indou.takao@...fujitsu.com, caoj.fnst@...fujitsu.com
Subject: Re: [PATCH v9 5/8] x86/boot: Add get_acpi_rsdp() to parse RSDP in
 cmdlien from kexec

On 10/17/18 at 06:20pm, Chao Fan wrote:
> If KEXEC write the RSDP pointer to cmdline, parse the cmdline
> and use it.
> Imitate from early_param of "acpi_rsdp".
> 
> Signed-off-by: Chao Fan <fanc.fnst@...fujitsu.com>
> ---
>  arch/x86/boot/compressed/acpitb.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/arch/x86/boot/compressed/acpitb.c b/arch/x86/boot/compressed/acpitb.c
> index 50fa65cf824d..37b1f4407be8 100644
> --- a/arch/x86/boot/compressed/acpitb.c
> +++ b/arch/x86/boot/compressed/acpitb.c
> @@ -8,6 +8,9 @@
>  #include <linux/numa.h>
>  #include <linux/acpi.h>
>  
> +#define STATIC
> +#include <linux/decompress/mm.h>
> +
>  /* Search EFI table for RSDP table. */
>  static void efi_get_rsdp_addr(acpi_physical_address *rsdp_addr)
>  {
> @@ -200,3 +203,23 @@ static void bios_get_rsdp_addr(acpi_physical_address *rsdp_addr)
>  		*rsdp_addr = (acpi_physical_address)address;
>  	}
>  }
> +
> +static void get_acpi_rsdp(acpi_physical_address *rsdp_addr)
> +{
> +#ifdef CONFIG_KEXEC
> +	unsigned long long res;
> +	int len = 0;
> +	char *val;
> +
> +	val = malloc(20);

Why is the length 20? Defined a macro?

> +	len = cmdline_find_option("acpi_rsdp", val, 20);
> +
> +	if (len == -1)
> +		return;
> +
> +	if (len > 0) {
> +		val[len] = 0;
> +		*rsdp_addr = (acpi_physical_address)kstrtoull(val, 0, &res);
> +	}
> +#endif
> +}
> -- 
> 2.17.2
> 
> 
>