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Date:   Fri, 22 Jul 2022 15:49:04 +0800
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Subject: Re: [PATCH] LoongArch: Fix wrong "ROM Size" of boardinfo
To:     Tiezhu Yang <yangtiezhu@loongson.cn>,
        Huacai Chen <chenhuacai@kernel.org>
Cc:     WANG Xuerui <kernel@xen0n.name>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        loongarch@lists.linux.dev, linux-kernel@vger.kernel.org
References: <1658397181-2095-1-git-send-email-yangtiezhu@loongson.cn>
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From:   WANG Xuerui <kernel@xen0n.name>
In-Reply-To: <1658397181-2095-1-git-send-email-yangtiezhu@loongson.cn>
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On 2022/7/21 17:53, Tiezhu Yang wrote:
> We can see the "ROM Size" is different in the following outputs:
>
> [root@linux loongson]# cat /sys/firmware/loongson/boardinfo
> BIOS Information
> Vendor                  : Loongson
> Version                 : vUDK2018-LoongArch-V2.0.pre-beta8
> ROM Size                : 63 KB
> Release Date            : 06/15/2022
>
> Board Information
> Manufacturer            : Loongson
> Board Name              : Loongson-LS3A5000-7A1000-1w-A2101
> Family                  : LOONGSON64
>
> [root@linux loongson]# dmidecode | head -11
> ...
> Handle 0x0000, DMI type 0, 26 bytes
> BIOS Information
> 	Vendor: Loongson
> 	Version: vUDK2018-LoongArch-V2.0.pre-beta8
> 	Release Date: 06/15/2022
> 	ROM Size: 4 MB
>
> According to "BIOS Information (Type 0) structure" in the SMBIOS
> Reference Specification [1], it shows 64K * (n+1) is the size of
> the physical device containing the BIOS if the size is less than
> 16M.
>
> Additionally, we can see the related code in dmidecode [2]:
>
>    u64 s = { .l = (code1 + 1) << 6 };
>
> So the output of dmidecode is correct, the output of boardinfo
> is wrong, fix it.
>
> By the way, at present no need to consider the size is 16M or
> greater on LoongArch, because it is usually 4M or 8M which is
> enough to use.
Although the commit message is a bit Chinglish, the inclusion of code 
and snippets have all complemented the description, so overall it 
doesn't hamper understanding and I'm mostly okay with it.
>
> [1] https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.6.0.pdf
> [2] https://git.savannah.nongnu.org/cgit/dmidecode.git/tree/dmidecode.c#n347
>
> Fixes: 628c3bb40e9a ("LoongArch: Add boot and setup routines")
> Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
> ---
>   arch/loongarch/kernel/setup.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> index c74860b..8f5c2f9 100644
> --- a/arch/loongarch/kernel/setup.c
> +++ b/arch/loongarch/kernel/setup.c
> @@ -126,7 +126,7 @@ static void __init parse_bios_table(const struct dmi_header *dm)
>   	char *dmi_data = (char *)dm;
>   
>   	bios_extern = *(dmi_data + SMBIOS_BIOSEXTERN_OFFSET);
> -	b_info.bios_size = *(dmi_data + SMBIOS_BIOSSIZE_OFFSET);
> +	b_info.bios_size = (*(dmi_data + SMBIOS_BIOSSIZE_OFFSET) + 1) << 6;
>   
>   	if (bios_extern & LOONGSON_EFI_ENABLE)
>   		set_bit(EFI_BOOT, &efi.flags);

I've tested on real 3A5000 hardware and confirmed this is working.

$ cat /sys/firmware/loongson/boardinfo
BIOS Information
Vendor                  : Loongson
Version                 : vUDK2018-LoongArch-V2.0.pre-beta8
ROM Size                : 4096 KB
Release Date            : 06/15/2022

Board Information
Manufacturer            : Loongson
Board Name              : Loongson-LS3A5000-7A1000-1w-A2101
Family                  : LOONGSON64


So,

Reviewed-by: WANG Xuerui <git@xen0n.name>