linux-kernel - Re: [RFC PATCH] of: make MAX_RESERVED

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Date:   Thu, 22 Nov 2018 10:51:28 +0800
From:   Miles Chen <miles.chen@...iatek.com>
To:     Rob Herring <robh+dt@...nel.org>
CC:     Frank Rowand <frowand.list@...il.com>,
        <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>, <wsd_upstream@...iatek.com>
Subject: Re: [RFC PATCH] of: make MAX_RESERVED_REGIONS configurable

On Wed, 2018-11-21 at 10:39 -0600, Rob Herring wrote:
> On Wed, Nov 21, 2018 at 2:11 AM <miles.chen@...iatek.com> wrote:
> >
> > From: Miles Chen <miles.chen@...iatek.com>
> >
> > When we use more than 32 entries in /resered-memory,
> > there will be an error message: "not enough space all defined regions.".
> > We can increase MAX_RESERVED_REGIONS to fix this.
> >
> > commit 22f8cc6e3373 ("drivers: of: increase MAX_RESERVED_REGIONS to 32")
> > increased MAX_RESERVED_REGIONS to 32 but I'm not sure if increasing
> > MAX_RESERVED_REGIONS to 64 is suitable for everyone.
> >
> > In this RFC patch, CONFIG_MAX_OF_RESERVED_REGIONS is added and used as
> > MAX_RESERVED_REGIONS. Add a sanity test to make sure that
> > MAX_RESERVED_REGIONS is less than INIT_MEMBLOCK_REGIONS.
> > Users can configure CONFIG_MAX_OF_RESERVED_REGIONS according to their
> > need.
> 
> I don't want a kconfig option for this. I think it should be dynamic instead.
> 
> The current flow is like this:
> 
> for each reserved node:
>   - call memblock_reserve
>   - Add info to reserved_mem array
> 
> I think we should change it to:
> 
> for each reserved node:
>   - call memblock_reserve
>   - count number of nodes
> 
> Alloc array using memblock_alloc
> 
> for each reserved node:
>    - Add info to reserved_mem array
> 

thanks for your comment.

I reviewed the flow and it might be easier to count the
nodes and setup array first:

for each reserved node:
    - count number of nodes

Alloc array using memblock_alloc


for each reserved node:
   - call memblock_reserve
   - Add info to reserved_mem array

What do you think?

> Rob