On 14/12/2017 14:25, Philippe Mathieu-Daudé wrote:
> Yes, a SDHCI qtest is added in a later series (in C) using MMIO access:
> http://lists.nongnu.org/archive/html/qemu-devel/2017-12/msg02391.html
> 
> But to be sure the SDHCI is correct I needed a SD slave to behave
> correctly ;) Hence this "bus test".

You could also use the SPI interface for a lower-level test.

Paolo