Re: [Xen-devel] [PATCH v5 01/14] x86/boot: enumerate documentation for the x86 hardware_subarch

[Ingo Molnar <mingo@xxxxxxxxxx>]

* Luis R. Rodriguez <mcgrof@xxxxxxxxxx> wrote:

> Although hardware_subarch has been in place since the x86 boot
> protocol 2.07 it hasn't been used much. Enumerate current possible
> values to avoid misuses and help with semantics later at boot
> time should this be used further.
> 
> These enums should only ever be used by architecture x86 code,
> and all that code should be well contained and compartamentalized,
> clarify that as well.
> 
> v2: updates documentation further -- be a bit more pedantic about
>     annotating care and use of these guys.
> v3: Use s/SOC/SoC and also anntoate that both domU and dom0 are
>     both currently supported through the PV boot path.
> 
> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> Signed-off-by: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
> ---
>  arch/x86/include/uapi/asm/bootparam.h | 37 
> ++++++++++++++++++++++++++++++++++-
>  1 file changed, 36 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/uapi/asm/bootparam.h 
> b/arch/x86/include/uapi/asm/bootparam.h
> index 329254373479..bf9fea2f4591 100644
> --- a/arch/x86/include/uapi/asm/bootparam.h
> +++ b/arch/x86/include/uapi/asm/bootparam.h
> @@ -157,7 +157,42 @@ struct boot_params {
>       __u8  _pad9[276];                               /* 0xeec */
>  } __attribute__((packed));
>  
> -enum {
> +/**
> + * enum x86_hardware_subarch - x86 hardware subarchitecture

Could you add some prominent warning here, like:

> + * WARNING: the 'x86 subarch flag' is only used for legacy hacks, for 
> platform
> + *          features that are not easily enumerated or discoverable. You 
> should
> + *          not ever use this for new features.

Thanks,

        Ingo

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