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Sender: Minchan Kim <minchan.kim@gmail.com>
Date:   Fri, 20 Nov 2020 13:40:13 -0800
From:   Minchan Kim <minchan@kernel.org>
To:     Rui Salvaterra <rsalvaterra@gmail.com>
Cc:     ngupta@vflare.org, sergey.senozhatsky.work@gmail.com,
        linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5] zram: break the strict dependency from lzo
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On Fri, Nov 20, 2020 at 09:10:13AM +0000, Rui Salvaterra wrote:
> Hi, Minchan,
> 
> On Thu, 19 Nov 2020 at 22:26, Minchan Kim <minchan@kernel.org> wrote:
> >
> > What's the purpose of ZRAM_AUTOSEL_ALGO?
> > If you and Sergey already discussed, sorry about the missing it.
> 
> The purpose of ZRAM_AUTOSEL_ALGO is to make sure at least one of the
> required compression algorithms is enabled, either as a module or
> built-in. I believe Sergey agreed with the reasoning behind it, but
> he'll let us know if I misunderstood. :)
> 
> > Below doesn't work for your goal?
> 
> Unfortunately, it doesn't. :( It breaks the dependency chain, allowing
> you to deselect all compression algorithms in the crypto menu, and

Hi Rui,

I don't understand it. Please see below.  ZRAM_COMP_LZO_DEF select
CRYPTO_LZO, not relying on it. If system supports other CRYPTO module
it will show on choice list. Otherwise, default lzo will be always
there and select CRYPTO_LZO.

Do I miss your point?

+
+choice
+       prompt "zram default compressor"
+       default ZRAM_COMP_LZO_DEF
+       depends on ZRAM || CRYPTO_LZ4
+       help
+         a
+
+config ZRAM_COMP_LZO_DEF
+       bool "lzo"
+       select CRYPTO_LZO
+       help
+         b
+
+config ZRAM_COMP_LZ4_DEF
+       bool "lz4"
+       depends on CRYPTO_LZ4
+       help
+         c
+endchoice
+
+config ZRAM_DEF_COMP
+       string
+       default "lzo" if ZRAM_COMP_LZO_DEF
+       default "lz4" if ZRAM_COMP_LZ4_DEF