Re: LG Nexus 5

[Jared McNeill <jmcneill%invisible.ca@localhost>]

Hi Shao --

You should not have to change initarm(). You can introduce SoC specific 
initialization using the ARM_PLATFORM macro. Have a look at 
arch/arm/sunxi/sunxi_platform.c, arch/arm/ti/omap3_platform.c for 
examples. This will handle any SoC specific early init, nonstandard MP 
startup, timers, reset handling, etc.

Getting your framebuffer to work should require little to no code:

 - Your bootloader is responsible for setting up the display and creating
   a linear framebuffer.
 - In your FDT, declare a node under /chosen (lets keep it simple and call
   it /chosen/framebuffer) with a compatible string of
   "simple-framebuffer" and describing the linear FB setup by the
   bootloader using the simple-framebuffer bindings[1]

NetBSD's simplefb driver (sys/arch/arm/fdt/arm_simplefb.c and 
sys/dev/fdt/simplefb.c) will do the rest for you.

Hope this helps,
Jared

[1] https://www.kernel.org/doc/Documentation/devicetree/bindings/display/simple-framebuffer.yaml


On Fri, 4 Nov 2022, Shao Miller wrote:

> Maybe this question just above was a silly one.  I have a framebuffer region 
> of memory and I have successfully drawn lines on the display from the 
> aforementioned initarm().  Perhaps there's some way I can attach something 
> with the name genfb in it at such an early stage, in order for early prints 
> to work, and doing so will remove any need for me to process a font and draw 
> it myself?
>
> A new question: what's your favourite guide to follow for porting NetBSD to 
> some hardware using the FDT approach?  I've examined the non-FDT 
> https://www.netbsd.org/docs/kernel/porting_netbsd_arm_soc.html article, so 
> far.
>
> Thank you for any time you can spare.
>
> - Shao Miller