gtkguitune relies on the OSS interface at /dev/dsp. However, when I got this program to work, it was thoroughly unusable to tune a guitar even in ideal acoustic circumstances, so my suggestion would be to just drop it. Reproducible: Always Steps to Reproduce: 1. Compile and boot your kernel with CONFIG_SND_PCM_OSS disabled 2. Start gtkguitune 3. gtkguitune complains about not finding /dev/dsp and exists
Created attachment 916189 [details] Screen capture of gtkguitune in use, absolutely failing to show the pitch of the guitar in the designated meter even when fiddling with the (undocumented) settings