Date:   Mon, 6 Mar 2023 12:28:36 +0000
From:   "Russell King (Oracle)" <linux@armlinux.org.uk>
To:     Jungseung Lee <js07.lee@samsung.com>
Cc:     linus.walleij@linaro.org, amit.kachhap@arm.com, ardb@kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        keescook@chromium.org, js07.lee@gmail.com
Subject: Re: [PATCH 2/2] arm/mm : Report actual image regions in /proc/iomem
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Sender: Russell King (Oracle) <linux@armlinux.org.uk>
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On Mon, Mar 06, 2023 at 09:14:23PM +0900, Jungseung Lee wrote:
> Hi, Russell
> 
> > -----Original Message-----
> > From: Russell King (Oracle) <linux@armlinux.org.uk>
> > Sent: Monday, March 6, 2023 8:10 PM
> > To: Jungseung Lee <js07.lee@samsung.com>
> > Cc: linus.walleij@linaro.org; amit.kachhap@arm.com; ardb@kernel.org;
> > linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org;
> > keescook@chromium.org; js07.lee@gmail.com
> > Subject: Re: [PATCH 2/2] arm/mm : Report actual image regions in
> > /proc/iomem
> > 
> > On Mon, Mar 06, 2023 at 02:51:55PM +0900, Jungseung Lee wrote:
> > >  The resource reservations in /proc/iomem made for the kernel image
> > > did  not reflect the gaps between text, rodata, and data.
> > >  Add the "rodata" resource and update the start/end calculations.
> > >
> > >  Before :
> > > 04000000-2f7fffff : System RAM
> > >   04100000-04cfffff : Kernel code
> > >   04e00000-05369a27 : Kernel data
> > >
> > >  After :
> > > 04000000-2f7fffff : System RAM
> > >   04100000-049fffff : Kernel code
> > >   04a00000-04cb2fff : Kernel rodata
> > >   04e00000-05369a27 : Kernel data
> > 
> > NAK. This is API, and programs do read and parse this file. It is
> > important that this file reports these parameters in a similar way to
> > other architectures. Other architectures do not split up the
> > individual regions.
> > 
> 
> Sounds like an important point, but I failed to find which programs use it
> as an API. Could you tell me which program uses it as an API?
> 
> In fact, x86 architecture also split up the individual regions in this way.
> In addition, most architectures separate the "Kernel bss" area, but arm does
> not.

Take a look at kexec-tools - that certainly does parse /proc/iomem
looking for entries such as "Kernel code" and "Kernel data".

It's fine for an architecture to decide to do something else if it
started to do it early on, but not when something has been established
for decades.

-- 
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