[U-Boot] [PATCH v2 11/11] New board support: Nokia RX-51 aka N900

[Marek Vasut]

Dear Pali Rohár,

> On Friday 01 June 2012 20:48:15 Marek Vasut wrote:
> > Dear Pali Rohár,
> > 
> > > On Monday 30 April 2012 16:37:55 Tom Rini wrote:
> > > > On Sun, Apr 29, 2012 at 11:18:48AM +0200, Marek Vasut
> 
> wrote:
> > > > > Dear Pali Roh?r,
> > > > 
> > > > [snip]
> > > > 
> > > > > > Also onenand code working fine, but when is enabled
> > > > > > u-boot
> > > > > > binary is too big and cannot be flashed into this
> > > > > > device.
> > > > > > But for testing in qemu or booting u-boot with enabled
> > > > > > onenand support stored in mmc via flashed u-boot (with
> > > > > > disabled onenand support) working too.
> > > > > > 
> > > > > > Is there way how to decrease u-boot binary size?
> > > > > 
> > > > > Try compiling it in thumb mode? I think Tom Rini added
> > > > > support for that and tested it on omap.
> > > > 
> > > > Aneesh V did the real work for thumb mode for omap4/5, I
> > > > just
> > > > picked it up and addressed some comments.  It's currently
> > > > in
> > > > u-boot-arm/master.
> > > 
> > > But N900 is omap3. Has u-boot thumb support for omap3 boards
> > > too?
> > 
> > OMAP3 has the same (CortexA8) core, it will work on it too.
> > Dunno if it's enabled for OMAP3 now, but it shouldn't be hard
> > to do so.
> > 
> > Best regards,
> > Marek Vasut
> 
> There is one HW problem with thumb on N900: thumb mode is buggy
> and thumb compiled applications crashing.

What? Is it the CPU being buggy?

> But finaly last month
> we found solution for this problem. Errata 430973 workaround,

Errata of what?

> calling uboot function omap3_emu_romcode_call for setting IBE bit
> in AUX CR.

What exactly does it do?

> So now Ubuntu (which is thumb compiled) booting and
> working.

Urh.

> So for using thumb mode on N900 we first need to call first that
> function. It is possible to build u-boot in some mixed mode (some
> parts in arm and some in thumb)?

That's what you usually do -- you always start in ARM mode, then you switch to 
thumb mode. It's possible to mix thumb and arm of course, that's what normally 
happens.

> Now omap3_emu_romcode_call is
> called from misc_init_r rx51 board code.

So this problem isn't present on all omap3s ?

Best regards,
Marek Vasut