Re: Guix on Mobile (Was: Interest check: U-Boot bootloader support)

[Jookia <166291@gmail.com>]

On Mon, Feb 22, 2016 at 09:17:56PM +0100, Danny Milosavljevic wrote:
> Hi,

Hey!

> > Basically the bootloader would just be Linux to do some hardware init (touch screen, etc)

> Actually, on ARM you usually have to do basic hardware init before Linux runs. 
> Linux doesn't do it all. Often, booting Linux without U-Boot doesn't work.
> 
> On linux-sunxi, U-Boot initializes some clocks, memory, important regulators, USB, MMC and the framebuffer (I'm sure I forgot some). 
> 
> U-Boot started out as just a tiny copy of Linux, but it has diverged a bit since.

This is true, I should've said that it'd go from u-boot -> linux. Rather than,
u-boot -> grub -> linux. The advantage here is Linux can do initialization of
things like the screen or touchpad.

> There are also weird things like you aren't allowed to turn stuff you need later off (in, say, U-Boot), because once it's off, you can't turn it on again (because it's off, duh) without rebooting. So kexeced Linux can find itself in a world of hurt. 
> 
> (There's a special data-passing mechanism between U-Boot and Linux in order to mitigate that problem - but does it work between Linux and kexec-Linux?)

Not sure you'd need to do that if you're already in a set up Linux?

> > systems with GRUB and U-Boot as Linux tends to initialize hardware better than
> > them (neither U-Boot nor Libreboot like either of the EDID values of my screen!)
> > and would probably allow faster bootup given you're not initializing the
> > hardware twice.
> 
> I also have a screen with wrong EDID. I have a DVI<->HDMI adapter by ATI which contains an EDID chip in order to fake the data in order to get it to work. How insane is that?

Insane!

> That said, on the general interest: guix is already slooow on a fairly modern X200. If that ran on an armv7, it would probably be much slower. Not fun. 
> 
> But might be worth a try. Did someone try the non-GuixSD armv7 thing? Is the speed acceptable?

I already run NixOS on ARM as my desktop machine, not sure how much slower
GuixSD would be. On a phone, though it could be much worse.

Jookia.