[Tinkerphones] LetuxOS for Rasi-Zero-W?

[David Boddie]

On Thursday, 9 September 2021 14:18:50 CEST H. Nikolaus Schaller wrote:

> But in the meantime I got another hint: maybe the same reason why the SD
> size limits exist.
> 
> Pi 0, 1, 2 use an ARMv6 while the others (except Pi 4) use ARMv7.

I assumed you already knew about that. :-)

I think 2 uses an ARMv7 core:

https://en.wikipedia.org/wiki/Raspberry_Pi#Specifications

> This finally explained to me why there is kernel.img and kernel7.img...
> It is not strictly necessary to have two kernel builds and it turned out
> that changing the letux_defconfig from
> 
> # CONFIG_ARCH_MULTI_V6 is not set
> CONFIG_ARCH_MULTI_V7=y
> CONFIG_ARCH_MULTI_V6_V7=y
> 
> to
> 
> CONFIG_ARCH_MULTI_V6=y
> CONFIG_ARCH_MULTI_V7=y
> CONFIG_ARCH_MULTI_V6_V7=y
> 
> makes the kernel start on both :) Well, there are differences
> (single core vs. quad core, different memory size etc.) but this
> is taken care of by device tree and kernel.
> 
> But it fails running the Debian rootfs binaries (at least the
> one I have tried so far). The same µSD plugged into the 3b+ boots
> and runs fine.
> 
> So there must be something special in Raspbian or Debian for ARMv6.

My understanding was that Raspbian was initially a complete rebuild of Debian
for ARMv6.

According to the Debian Wiki:

  "Raspberry Pi OS builds a single image for all of the Raspberry families,
   so you will get an armhf 32-bit, hard floating-point system, but built for
   the ARMv6 ISA (with VFP2), unlike Debian's ARMv7 ISA (with VFP3) port."

[https://wiki.debian.org/RaspberryPi]

So it's likely that stock Debian binaries won't run on a Pi Zero.

David