linux-kernel - Re: [PATCH] x86: Add a prompt for HPET_EMULATE

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Message-ID: <ec6caa23-28d6-9695-2b0f-b3ba9ef28b60@infradead.org>
Date:   Wed, 3 Feb 2021 19:47:30 -0800
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Anand K Mistry <amistry@...gle.com>, x86@...nel.org
Cc:     Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: Add a prompt for HPET_EMULATE_RTC

On 2/3/21 6:21 PM, Anand K Mistry wrote:
> This does two things:
> 1. Makes the option visible in menuconfig, allowing the user to easily
>    disable this option
> 2. Allows olddefconfig to respoct the option if it is set in the old
>    .config file
> 
> It's not clear exactly why the second consequence is true, but it
> appears to be because when the conf tool reads the config file, it only
> respects the existing setting if the option is "visible" (see
> scripts/kconfig/symbol.c:381).
> 
> Signed-off-by: Anand K Mistry <amistry@...gle.com>
> ---

Hi,

When you run "make olddefconfig", should this "depends on"
line evaluate to true or false?
I.e., what are the settings of these symbols in the old .config file?


  	depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)

If not, is there some out-of-tree driver involved?
I'm having a little trouble seeing why this is needed.


>  arch/x86/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 21f851179ff0..28f814493c7b 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -890,6 +890,7 @@ config HPET_TIMER
>  
>  config HPET_EMULATE_RTC
>  	def_bool y
> +	prompt "HPET RTC emulation"
>  	depends on HPET_TIMER && (RTC=y || RTC=m || RTC_DRV_CMOS=m || RTC_DRV_CMOS=y)
>  
>  config APB_TIMER
> 


thanks.
-- 
~Randy