Re: [PATCH v2 3/3] tmem: allow tmem to be disabled with Kconfig

From: "Jan Beulich" <JBeulich@suse.com>
To: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>,
	Keir Fraser <keir@xen.org>, Doug Goldstein <cardoe@cardoe.com>,
	xen-devel@lists.xen.org
Subject: Re: [PATCH v2 3/3] tmem: allow tmem to be disabled with Kconfig
Date: Wed, 16 Mar 2016 02:39:02 -0600	[thread overview]
Message-ID: <56E929B602000078000DCF2E@prv-mh.provo.novell.com> (raw)
In-Reply-To: <20160316073506.GA31125@char.us.oracle.com>

>>> On 16.03.16 at 08:35, <konrad.wilk@oracle.com> wrote:
> On Tue, Mar 15, 2016 at 03:18:50PM -0500, Doug Goldstein wrote:
>> Wrap the various tmem functions with the Kconfig generated CONFIG_TMEM
>> option allowing users to build Xen without tmem support.
> 
> I ended with this change on top of yours (which I will squash):
> 
> The 'bool "tmem" so that if I did make an change in .config
> file it would still take effect even if I forgot XEN_CONFIG_EXPERT.
> 
> Otherwise it would keep on making it
> 
> CONFIG_TMEM=y
> instead of the
> 
> # CONFIG_TMEM is not set.
> 
> which I wrote in the .config file.
> 
> From b9d173eb0e0e1274c784fde5580b119d6f7b4bdc Mon Sep 17 00:00:00 2001
> From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> Date: Wed, 16 Mar 2016 03:28:39 -0400
> Subject: [PATCH] squash!     tmem: allow tmem to be disabled with Kconfig
> 
> ---
>  xen/common/Kconfig | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/xen/common/Kconfig b/xen/common/Kconfig
> index 39b0fa7..5bd8a84 100644
> --- a/xen/common/Kconfig
> +++ b/xen/common/Kconfig
> @@ -87,16 +87,21 @@ config LATE_HWDOM
>  
>  	  If unsure, say N.
>  
> -# Enables transactional memory support
> +# Enables transcendent memory support
>  config TMEM
>  	def_bool y
> -	prompt "Transactional Memory Support" if EXPERT = "y"
> +	bool "tmem"
> +	prompt "Transcendent Memory Support" if EXPERT = "y"
>  	---help---
>  	  Transcendent memory allows PV-aware guests to collaborate on memory
>  	  usage. Guests can 'swap' their memory to the hypervisor or have an
>  	  collective pool of memory shared across guests. The end result is
>  	  less memory usage by guests allowing higher guest density.
>  
> +	  You also have to enable it on the Xen commandline by using tmem=1
> +
> +	  If unsure, say Y.

But that will, afaict, disable tmem by default. Forgetting to set
XEN_CONFIG_EXPERT is, well, a mistake that results in a config
change just like the one you've observed.

Jan

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel