Re: [PATCH RFCv2 03/15] xen/arm: p2m: Replace level_{orders, masks} arrays with LEVEL_{ORDER, MASK}

From: Julien Grall <julien@xen.org>
To: Stefano Stabellini <sstabellini@kernel.org>
Cc: xen-devel@lists.xenproject.org, Wei.Chen@arm.com,
	Henry.Wang@arm.com, Penny.Zheng@arm.com,
	Bertrand.Marquis@arm.com, Julien Grall <jgrall@amazon.com>,
	Volodymyr Babchuk <Volodymyr_Babchuk@epam.com>
Subject: Re: [PATCH RFCv2 03/15] xen/arm: p2m: Replace level_{orders, masks} arrays with LEVEL_{ORDER, MASK}
Date: Wed, 12 May 2021 15:39:05 +0100	[thread overview]
Message-ID: <42315452-0fd3-9cc7-3fb7-89a840f94792@xen.org> (raw)
In-Reply-To: <alpine.DEB.2.21.2105111528180.5018@sstabellini-ThinkPad-T480s>

Hi Stefano,

On 11/05/2021 23:33, Stefano Stabellini wrote:
> On Sun, 25 Apr 2021, Julien Grall wrote:
>> From: Julien Grall <jgrall@amazon.com>
>>
>> The array level_orders and level_masks can be replaced with the
>> recently introduced macros LEVEL_ORDER and LEVEL_MASK.
>>
>> Signed-off-by: Julien Grall <jgrall@amazon.com>
> 
> So you actually planned to use LEVEL_ORDER and LEVEL_MASK in the xen/
> code. I take back the previous comment :-)
> 
> Is the 4KB size "hiding" (for the lack of a better word) done on purpose?
> 
> Let me rephrase. Are you trying to consolidate info about pages being
> 4KB in xen/include/asm-arm/lpae.h ?

THIRD_ORDER, SECOND_ORDER... is already not very 4KB specific :). In 
this case, what I am trying to do is completely removing the static 
arrays so they don't need to be global (or duplicated) when adding 
superpage support for Xen PT (see a follow-up patch).

This also has the added benefits to replace a with a couple of loads 
with only a few instructions working on immediates.

> 
> In any case:
> 
> Acked-by: Stefano Stabellini <sstabellini@kernel.org>

Thank you!

Cheers,

-- 
Julien Grall