linux-kernel - Re: [PATCH v3] zram: break the strict dependency from lzo

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Message-ID: <20201028182158.GA128655@google.com>
Date:   Thu, 29 Oct 2020 03:21:58 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Rui Salvaterra <rsalvaterra@...il.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>,
        minchan@...nel.org, ngupta@...are.org,
        linux-kernel@...r.kernel.org, linux-block@...r.kernel.org
Subject: Re: [PATCH v3] zram: break the strict dependency from lzo

Hi,

On (20/10/28 11:25), Rui Salvaterra wrote:
> > diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
> > index fe7a4b7d30cf..f93eed40e155 100644
> > --- a/drivers/block/zram/Kconfig
> > +++ b/drivers/block/zram/Kconfig
> > @@ -2,7 +2,7 @@
> >  config ZRAM
> >         tristate "Compressed RAM block device support"
> >         depends on BLOCK && SYSFS && ZSMALLOC && CRYPTO
> > -       select CRYPTO_LZO
> > +       depends on (CRYPTO_LZO || CRYPTO_LZ4 || CRYPTO_LZ4HC || CRYPTO_842 || CRYPTO_ZSTD)
> 
> This reverses the dependency order, as now we have to select a
> supported compression algorithm in order for zram to be visible in the
> block device drivers list.

Right, but well we also need to select ZSMALLOC and CRYPTO for
zram to become visible (the thing that I found out recently is
that you can always check the hidden/blocked items by hitting
'z' in menuconfig).

> This is why I wrote the ZRAM_AUTOSEL_ALGO
> kconfig symbol, which automatically selects lzo as a fallback. If the
> user chooses to select another supported algorithm, he will then be
> allowed to deselect lzo. We thus follow the principle of least
> surprise, IMHO.

OK, makes sense.

	-ss