Re: [Bug #11342] Linux 2.6.27-rc3: kernel BUG at mm/vmalloc.c - bisected

[Jamie Lokier]

Bernd Petrovitsch wrote:
> > 32MB no-MMU ARM boards which people run new things and attach new
> > devices to rather often - without making new hardware.  Volume's too
> > low per individual application to get new hardware designed and made.
> 
> Yes, you may have several products on the same hardware with somewhat
> differing requirements (or not). But that is much less than a general
> purpose system IMHO.

It is, but the idea that small embedded systems go through a 'all
components are known, drivers are known, test and if it passes it's
shippable' does not always apply.

> > I'm seriously thinking of forwarding porting the 4 year old firmware
> > from 2.4.26 to 2.6.current, just to get new drivers and capabilities.
> 
> That sounds reasonable (and I never meant maintaining the old system
> infinitely.

Sounds reasonable, but it's vetoed for anticipated time and cost,
compared with backporting on demand.  Fair enough, since 2.6.current
doesn't support ARM no-MMU last I heard ('soon'?).

On the other hand, the 2.6 anti-fragmentation patches, including
latest SLUB stuff, ironically meant to help big machines, sound really
appealing for my current problem and totally unrealistic to
backport...

> ACK. We avoid MMU-less hardware too - especially since there is enough
> hardware with a MMU around.

I can't emphasise enough how much difference MMU makes to Linux userspace.

It's practically: MMU = standard Linux (with less RAM), have everything.
No-MMU = lots of familiar 'Linux' things not available or break.

-- Jamie
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