linux-kernel - Re: [RESEND PATCH] scsi: ufs: sysfs: support writing boot

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Date:   Mon, 6 Jun 2022 11:48:01 +0900
From:   Damien Le Moal <damien.lemoal@...nsource.wdc.com>
To:     Bart Van Assche <bvanassche@....org>,
        Avri Altman <Avri.Altman@....com>,
        Caleb Connolly <caleb.connolly@...aro.org>,
        "a5b6@...eup.net" <a5b6@...eup.net>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        "James E . J . Bottomley" <jejb@...ux.ibm.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        "linux-scsi@...r.kernel.org" <linux-scsi@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:     "~postmarketos/upstreaming@...ts.sr.ht" 
        <~postmarketos/upstreaming@...ts.sr.ht>,
        "phone-devel@...r.kernel.org" <phone-devel@...r.kernel.org>
Subject: Re: [RESEND PATCH] scsi: ufs: sysfs: support writing boot_lun attr

On 6/5/22 12:55, Bart Van Assche wrote:
> On 6/1/22 10:05, Avri Altman wrote:
>> As a design rule, sysfs attribute files should not be used to make
>> persistent modifications to a device configuration. This rule applies
>> to all subsystems and ufs is no different.
> 
> Hmm ... where does that rule come from? I can't find it in
> Documentation/admin-guide/sysfs-rules.rst. Did I perhaps overlook something?

I am not aware of any writable sysfs attribute file that can be used to
make persistent device configuration changes, at least in storage area.
I know of plenty that do change a device setting, but without saving this
setting to maintain it across power cycles. Do you know of any such
attribute ? I was under the impression that sysfs should not be used to
persistently reconfigure a device...

-- 
Damien Le Moal
Western Digital Research