Kernel configuration options

[Bernardo Innocenti]

John Richard Moser wrote:
> Bernardo Innocenti wrote:
>> John Richard Moser wrote:

>>>   (Do I need a developer's key or smth?)
>> Yes, you do need a developer key.  What is an smth?
> 
> something

Gosh, as you might have guessed, I'm not a native
English speaker :-)


>> Not on the Geode: we don't have MTRRs, so I guess the kernel
>> is being mapped by 4KB pages.
> 
> Remove hugetlbfs then.

Good point.


> Would you boot off the kernel on the flash and then load the system from 
> the USB or SD, or use a kernel on the SD card?

You could do both ways by tweaking the olpc.fth boot script
as you wish.  But I guess keeping the kernel with its OS
would be the way to go in most cases.


> So this raises the question:  By parallelizing boot and using an 
> event-driven init system like Ubuntu's Upstart, could you actually get 
> to running application code before loading the modules; and then set up 
> all the hardware while more CPU-bound parts of the boot process run?

As someone said a few days ago (was it dwmw?), there's not much
you can gain by parallelizing boot on the XO, because I/O on the
flash is pretty much synchronous and CPU bound.  And we only have
one CPU, of course.

But it turns out that running X very soon during the startup
process is quite easy.  People do not realize that, by today
standards, the X server is a very small program.  It starts
in less than one second off warm buffer caches.  And, more
importantly, it has almost no external dependencies.

SIDE NOTE: some genius recently made the X server depend on
OpenSSL in git so they could use MD5 as a hashing algorithm
for traditional fonts.  But I guess someone will undo this
brain damage soon or later :-)

 
> Sort of bring up the system while all the devices are being initialized, 
> just as long as graphics + keyboard + mouse are up for X to start when 
> it gets there.

No need to wait for input devices before you start X: with the
new input hotplug system, you can dynamically add mice and kbds
after the fact.

I was planning to do that for Update.2 if I ever find the time.

-- 
 \___/
 |___|   Bernardo Innocenti - http://www.codewiz.org/
  \___\  One Laptop Per Child - http://www.laptop.org/