Re: [PATCH] LoongArch: Correct the calculation logic of thread_count

[Qiang Ma]

在 2025/11/26 12:49, Huacai Chen 写道:
> Hi, Qiang,
>
> On Wed, Nov 26, 2025 at 10:37 AM Qiang Ma <maqianga@xxxxxxxxxxxxx> wrote:
> > For thread_count, the current calculation method has a maximum of 255,
> > which may not be sufficient in the future. Therefore, we are correcting
> > it now.
> I think you should contact the Loongson BIOS team to confirm they will do so.

I contacted Li Chao from the Loongson BIOS team and had a brief 
communication.

bios will do this when it exceeds 256.

> And we can hardly meet the case that one socket contains more than 256
> cores (this is different from the case MAX_CPUS > 256)
According to Li Chao, the 256 logic core on a single chip should arrive 
in the next generation.
> Huacai
>
> > Reference: SMBIOS Specification, 7.5 Processor Information (Type 4)[1]
> >
> > [1]: https://www.dmtf.org/sites/default/files/standards/documents/DSP0134_3.9.0.pdf
> >
> > Signed-off-by: Qiang Ma <maqianga@xxxxxxxxxxxxx>
> > ---
> >   arch/loongarch/kernel/setup.c | 9 ++++++++-
> >   1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/loongarch/kernel/setup.c b/arch/loongarch/kernel/setup.c
> > index 25a87378e48e..760f5ce44384 100644
> > --- a/arch/loongarch/kernel/setup.c
> > +++ b/arch/loongarch/kernel/setup.c
> > @@ -56,6 +56,7 @@
> >   #define SMBIOS_FREQLOW_MASK            0xFF
> >   #define SMBIOS_CORE_PACKAGE_OFFSET     0x23
> >   #define SMBIOS_THREAD_PACKAGE_OFFSET   0x25
> > +#define SMBIOS_THREAD_PACKAGE_2_OFFSET 0x2E
> >   #define LOONGSON_EFI_ENABLE            (1 << 3)
> >
> >   unsigned long fw_arg0, fw_arg1, fw_arg2;
> > @@ -120,13 +121,19 @@ static void __init parse_cpu_table(const struct dmi_header *dm)
> >   {
> >          long freq_temp = 0;
> >          char *dmi_data = (char *)dm;
> > +       u8 thread_count;
> > +       u16 thread_count2;
> >
> >          freq_temp = ((*(dmi_data + SMBIOS_FREQHIGH_OFFSET) << 8) +
> >                          ((*(dmi_data + SMBIOS_FREQLOW_OFFSET)) & SMBIOS_FREQLOW_MASK));
> >          cpu_clock_freq = freq_temp * 1000000;
> >
> >          loongson_sysconf.cpuname = (void *)dmi_string_parse(dm, dmi_data[16]);
> > -       loongson_sysconf.cores_per_package = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
> > +       thread_count = *(dmi_data + SMBIOS_THREAD_PACKAGE_OFFSET);
> > +       thread_count2 = *(u16 *)(dmi_data + SMBIOS_THREAD_PACKAGE_2_OFFSET);
> > +       if (thread_count != 0)
> > +               loongson_sysconf.cores_per_package = dm->length >= 0x30 && thread_count == 0xFF ?
> > +                                                    thread_count2 : thread_count;
> >
> >          pr_info("CpuClock = %llu\n", cpu_clock_freq);
> >   }
> > --
> > 2.20.1