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From:   Huacai Chen <chenhuacai@kernel.org>
Date:   Fri, 22 Jul 2022 15:53:13 +0800
Message-ID: <CAAhV-H4B1cZD5a2NMpRE5Nbm=tGPsTf8xA5A+CohsQia3vwtuQ@mail.gmail.com>
Subject: Re: [PATCH] LoongArch: Fix wrong "ROM Size" of boardinfo
To:     WANG Xuerui <kernel@xen0n.name>
Cc:     Tiezhu Yang <yangtiezhu@loongson.cn>,
        Jiaxun Yang <jiaxun.yang@flygoat.com>,
        loongarch@lists.linux.dev, LKML <linux-kernel@vger.kernel.org>
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Hi, Tiezhu,

If this patch is really needed, please also send a patch for our
internal LTS kernel repo, thanks.

Huacai

On Fri, Jul 22, 2022 at 3:49 PM WANG Xuerui <kernel@xen0n.name> wrote:
>
> 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>
>
>