[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: armel/marvell kernel size

On Tue, 2018-03-27 at 02:30 -0300, Rogério Brito wrote:
> > > I will see if all the modules make sense for an embedded system like this
> > > and I will send a list of options for opinions by others...
> > 
> > [...]
> > 
> > As I see it, the point of installing Debian on little NAS boxes is to
> > break out of the restrictions of an embedded system.  We try to
> > provide, so far as possible, the same features across all
> > architectures.
> It sure makes sense to provide a lot more than some kernels, but I am
> curious about some features that end up as modules like some
> framebuffer like the following:
> (...)
> # CONFIG_FB_MATROX is not set
> # CONFIG_FB_RADEON is not set
> # CONFIG_FB_ATY128 is not set
> # CONFIG_FB_ATY is not set
> # CONFIG_FB_SAVAGE is not set
> # CONFIG_FB_SIS is not set
> # CONFIG_FB_NEOMAGIC is not set
> # CONFIG_FB_KYRO is not set
> # CONFIG_FB_3DFX_ACCEL is not set
> # CONFIG_FB_VOODOO1 is not set
> (...)
> Is there any reason why, say, a driver for an S3 card is enabled while
> not for a Matrox?

I don't know; that doesn't make a lot of sense.

The Kirkwood SoCs have external PCIe links and some of the supported
devices (like OpenRD) provide PCIe expansion slots, so most PCIe device
drivers should be enabled.

> Are there real users for those? I know that, as
> modules, they don't make the kernel bigger, but they sit there on
> disk, doing nothing (right?).

They probably don't make a difference.  However there are some cases
where a modular driver may require (and select) a feature that is
always built-in.

> Similarly for wifi cards like those Intel ones like iwlwifi (which is
> the one that I have in this Core 2 Duo here)...

Prepare to be amazed: https://www.amazon.com/dp/B00OM0L9ZO

> OK, now to the real meat of my message.  Regarding shrinking the
> kernel image, I was able to tweak things slightly (drop from 101% down
> to 98%) by disabling APPARMOR, YAMA, AUDIT, making the kernel use the
> deadline IO scheduler instead of the CFQ and making as modules the
> ones that you suggested in the original message... Is that acceptable?

I would really rather we avoided disabling AppArmor, since it is not
only built-in but also enabled by default on all other architectures. 
Still, as armel will not be a release architecture any more, I suppose
it can diverge further from the normal configuration.

> If so, then I will test them on my Kurobox Pro and report what works
> and what breaks. I just wanted to get things smaller by tackling some
> lower hanging fruit...
> Another point: from what I saw in the Debian scripts, not all
> armel/marvell systems are limited to 2MB (in particular, the Kurobox
> Pro with which I am most concerned still has 630KB of room)...

Roger has increased the size limit to 2729712 on the sid branch, which
is the limit on the Buffalo Linkstation devices.  Check whether that
matches the Kurobox Pro too.

> In the
> very worst case (of course, this is not what we want), if the kernel
> actually gets much bigger in time for the buster release, we could
> selectively drop some systems (like what was done with the DNS323)
> instead of dropping an entire arch... I even think that a new,
> smaller, alternative flavor of the kernel is possible to provide to
> support those systems that are limited to 2MB of kernel image... (I
> can commit to support that, if my initial ideas work and people accept
> them).

Either of those seem like reasonable options.


> Of course, if we could make some real magic and make our kernels much,
> much smaller to support back the DNS323, that would be amazing... :-)
> I guess that I will look into those LTO patches in the future...
> OK, I am sending this to see if those ideas make sense, to offer my
> help and, of course, to get some feedback.

Ben Hutchings
For every complex problem
there is a solution that is simple, neat, and wrong.

Attachment: signature.asc
Description: This is a digitally signed message part

Reply to: