~irimi1/gemini-pda-docs

fd858d74d9b8ed4ec18c9f10aacf052a3fef289e — Manuel Groß 2 years ago 181dfce
Add architecture info
1 files changed, 12 insertions(+), 0 deletions(-)

M docs/images.md
M docs/images.md => docs/images.md +12 -0
@@ 44,6 44,18 @@ I know nothing more about that than the [wiki I’m referencing](https://github.

The image files used to boot are Android boot images assembled using `mkbootimg`, which makes sense, considering that the `LK` bootloader is used in Android as well. The [gemian wiki](https://github.com/gemian/gemini-keyboard-apps/wiki/KernelCompilation) describes how such an image is built.

## Architecture

The Helios X25/X27 is an arm64 SoC supporting ARMv8. In the Gemian Wiki, the kernel is compiled using a prebuilt aarch64-cross-toolchain for `ARCH=arm64`. This should be applicable for userspace as well.

The byte order of the CPU is little endian, which you can check via `lscpu` on any provided Linux image, or this little trick in [termux](https://termux.com/) (`lscpu` didn’t work for me there):

```
# Returns 1 for little endian, 0 for big endian
$ echo -n I | od -to2 | head -n1 | cut -f2 -d" " | cut -c6
1
```

## Sources

### dguidipc