linux-kernel - Re: [PATCH 2/3] x86 cpuinfo: implement sysfs nodes for x86

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Message-ID: <20191211142647.GB605616@kroah.com>
Date:   Wed, 11 Dec 2019 15:26:47 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Thomas Renninger <trenn@...e.de>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Felix Schnizlein <fschnizlein@...e.com>,
        linux-kernel@...r.kernel.org,
        Felix Schnizlein <fschnizlein@...e.de>,
        linux-arch@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux@...linux.org.uk, will.deacon@....com, x86@...nel.org
Subject: Re: [PATCH 2/3] x86 cpuinfo: implement sysfs nodes for x86

On Wed, Dec 11, 2019 at 03:12:51PM +0100, Thomas Renninger wrote:
> On Wednesday, December 11, 2019 2:56:19 PM CET Greg KH wrote:
> > On Wed, Dec 11, 2019 at 11:42:35AM +0100, Thomas Renninger wrote:
> > > If Greg (and others) are ok, I would add "page size exceeding" handling.
> > > Hm, quick searching for an example I realize that debugfs can exceed page
> > > size. Is it that hard to expose a sysfs file larger than page size?
> > 
> > No, there is a simple way to do it, but I'm not going to show you how as
> > it is NOT how to use sysfs at all :)
> >
> > Why are you wanting to dump this whole mess into one file
> 
> I wouldn't call a whitespace separated list of CPU feature flags a mess...

It's a mess in that it's more than one value and you want to overflow a
PAGE_SIZE sometime in the future with it :(

> > and then parse
> > it, it's no different from having 100+ different sysfs files and then
> > doing a readdir(3) on the thing, right?
> 
> If this is the way it "has to"/should/"is designed for" to export such
> (not that complex) data via sysfs...
> 
> I do not have such a strong opinion on the how, this is up to maintainers
> to discuss.
> 
> I hope it is agreed that this info is worth exporting via sysfs.

I don't think anyone is saying it is worth exporting this information
via sysfs at all here.

thanks,

greg k-h