Re: [Ksummit-discuss] [MAINTAINERS SUMMIT] Deprecation / Removal of old hardware support

[Lukasz Majewski <lukma@denx.de>]

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Hi Linus,

> Including Alexander Sverdlin, Lukasz Majewski  and Jonas
> Jensen here, they may or may not be able to share some of
> their industrial IoT experience. (Contract terms with vendors
> may make it necessary to stay silent sometimes.)

Thank you for putting me on CC.

> 
> On Mon, Sep 10, 2018 at 11:41 PM Arnd Bergmann <arnd@arndb.de> wrote:
> > On Mon, Sep 10, 2018 at 5:35 PM Linus Walleij
> > <linus.walleij@linaro.org> wrote:  
> 
> > > My ARMv4 is another example, but I can point at new devices
> > > beging deployed as we speak, using that ISA, even though it is
> > > from 1999. So it has many active users (and maintainers).  
> >
> > Note that even though gcc is dropping ARMv4 support from new
> > compilers, you can still use old toolchains, and there are tricks to
> > make ARMv4T binary code work on ARMv4. However, if gcc
> > ever stops supporting ARMv4T, this becomes a problem. My guess
> > is that will take another 10 years though, and we might have
> > removed some or all of the individual ARMv4 platforms by then.  
> 
> ARMv4 is becoming a trouble, not that it is hard to maintain,
> actually we're on top of things there. The problem is that among
> the FA526 systems from Faraday and the ARMv4T in EP93xx
> there are very serious IoT deployments that have been going
> on for soon 15 years and continuing.

The ARMv4T shall be supported. The 15 years may be a bare minimum for
some "heavy duty/industrial" systems...

It may happen that the same HW (certified already) will be used for 30+
years (with the SW BSP replaced a few times).

> 
> New MOXA ART ARMv4 FA526 systems are being deployed
> in buildings across the planet as we speak. They just replaced
> one in the office block where I sit, that is how I got to know.
> 
> These are mostly for ventilation and
> similar systems but also heavy duty from Liebherr controlling
> unspecified hydraulic systems. The ventilation systems are
> definately Internet-connected, I don't know about the others.

The "unspecified hydraulic systems" do have a way to update the SW
(which is already done).

> 
> These pose an increasing security threat, and for that reason
> I personally feel it is irresponsible to remove the option to
> create new kernels and upgrade these devices.

Frankly speaking the possibility to have the new kernel in a relatively
easy (and cheap) way was a strong motivator to add support to mainline.

> 
> I think for depreciation one has to be aware that some archs
> used in IoT deployments have life cycles of 20-30 or more years,
> whereas some tablet or handset SoCs may be something like
> 5 years maximum before maintainers get annoyed that you
> even use them.
> 
> Sometimes I get the feeling that people focused on desktops
> or servers suffer from velocitate (speed blindness) and think
> everybody is like them. (Well don't we all.)

I do must agree here. In general ARM9 (v4T) will stay with us for a
long, long time.

In the kernel community we pose a lot of attention to security (for
example the prompt reaction on meltdown/spectre), but in the same time
we tend to forget about the "long lived" devices and force their
maintainers to use 2.6.x kernels..... (or even 2.4.x).

> 
> With all the hoopla about IoT in the business right now since
> a year or two back, the question of their extremely long life
> cycle and effect on development has not really been
> considered AFAICT those are some of the most important
> systems to keep maintained.

+1

> 
> Yours,
> Linus Walleij




Best regards,

Lukasz Majewski

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