linux-kernel - Re: [PATCH v4 08/14] apm32: remove paravirt

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Message-ID: <57065BD4.3040209@oracle.com>
Date:	Thu, 7 Apr 2016 09:08:36 -0400
From:	Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:	"Luis R. Rodriguez" <mcgrof@...nel.org>, bp@...en8.de,
	hpa@...or.com, tglx@...utronix.de, mingo@...hat.com,
	rusty@...tcorp.com.au
Cc:	x86@...nel.org, linux-kernel@...r.kernel.org, luto@...capital.net,
	david.vrabel@...rix.com, konrad.wilk@...cle.com,
	xen-devel@...ts.xensource.com, lguest@...ts.ozlabs.org,
	andriy.shevchenko@...ux.intel.com, jlee@...e.com, glin@...e.com,
	matt@...eblueprint.co.uk, andrew.cooper3@...rix.com
Subject: Re: [PATCH v4 08/14] apm32: remove paravirt_enabled() use

On 04/06/2016 08:06 PM, Luis R. Rodriguez wrote:
> There is already a check for apm_info.bios == 0, the
> apm_info.bios is set from the boot_params.apm_bios_info.
> Both Xen and lguest, which are also the only ones that set
> paravirt_enabled to true, never set the apm_bios.info. The
>
> Xen folks are sure force disable to 0 is not needed,

Because apm_info lives in .bss (which we recently made sure is cleared 
on Xen PV). May be worth mentioning in the commit message so that we 
don't forget why this is not needed.

I think you also have this statement in other patches.

-boris

> we
> recently forced disabled this on lguest. With this in place
> the paravirt_enabled() check is simply not needed anymore.
>
> Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
> ---
>   arch/x86/kernel/apm_32.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/apm_32.c b/arch/x86/kernel/apm_32.c
> index 9307f182fe30..c7364bd633e1 100644
> --- a/arch/x86/kernel/apm_32.c
> +++ b/arch/x86/kernel/apm_32.c
> @@ -2267,7 +2267,7 @@ static int __init apm_init(void)
>   
>   	dmi_check_system(apm_dmi_table);
>   
> -	if (apm_info.bios.version == 0 || paravirt_enabled() || machine_is_olpc()) {
> +	if (apm_info.bios.version == 0 || machine_is_olpc()) {
>   		printk(KERN_INFO "apm: BIOS not found.\n");
>   		return -ENODEV;
>   	}