Okay, a final comment on the smem_len thing:
Someone (@pazos) recently ported FBink to BQ/Cervantes devices (which are based on the same NTX hardware as Kobos), and reported weird softlocks after a screen clear over the stock reading app.
I was doing that with a simple smem_len memset.
Turns out, when it can (i.e., @ 16bpp), the Qt Embedded driver they (and possibly others) use uses memory from the offscreen buffer to do... stuff.
I'm too lazy to dig into this much (c.f.,
https://github.com/bq/cervantes-qt/b...kfb/einkfb.cpp, size/psize vs. mapsize), so I'll be switching that memset to line_len * yres (and not yres_virtual like I'd like, because apparently Qt starts monopolizing memory potentially earlier than that).
AFAICT, the mmap is perfectly fine, though
.