Today I learned (re-learned?) that jmp_buf and sigjmp_buf are the same size in GNU libc on Linux, but vastly different sizes in the #Solaris libc:
https://gitlab.freedesktop.org/xorg/driver/xf86-video-intel/-/issues/228
(Fortunately we no longer ship this driver in #OracleSolaris, so this is just academic interest to me, not a bug I need to patch.)