This is Linux From Scratch, pinentry 0.9.7, pinentry -> pinentry-gtk-2, with
fallback to ncurses. No other pinentry program works.

This is KDE environment, Qt pinentry crashes. I can confirm that there's a
keyring password in the Login keyring, which is the only keyring I use.

Nonetheless, the password won't be asked again while the gpg-agent is running,
the password was entered at least once, and the "Remember password (or
whatever)" box was checked.

As soon as gpg-agent is terminated or a session restarted (which also terminates
gpg-agent), next time I try to use the pgp key, I get asked for its passphrase.