UCHCOM-DPRINTF: 0x06->0x00, 0x07->0x00
[zerolen] after uchcom_update_status with 0-byte device response:
[zerolen] sc_msr=0xff (expected high nibble from POISON 0xa5: ~0xA5&0x0F=0xA -> 0xA0|low)
[zerolen] TIOCMGET-visible modem bits (DCD/RI/DSR/CTS) = 0xf -- derived from UNINITIALIZED stack byte
UCHCOM-DPRINTF: 
[zerolen] uchcom_cfg_get_status -> msr=0xff (this is what ucom TIOCMGET hands to userspace)
UCHCOM-DPRINTF: 0x06->0x77, 0x07->0x00
[short1] after uchcom_update_status with 1-byte device response:
[short1] sc_msr=0x88 (expected high nibble from POISON 0xa5: ~0xA5&0x0F=0xA -> 0xA0|low)
[short1] TIOCMGET-visible modem bits (DCD/RI/DSR/CTS) = 0x8 -- derived from UNINITIALIZED stack byte
UCHCOM-DPRINTF: 
[short1] uchcom_cfg_get_status -> msr=0x88 (this is what ucom TIOCMGET hands to userspace)
UCHCOM-DPRINTF: 0x06->0x77, 0x07->0x77
[control] full-response path: sc_msr=0x88 (deterministic device bytes; no poison leak)