Hi, I have an Intel Atom E3930 system, /dev/ttyS6 device node is no longer exposed to the userspace starting from 4.15+ Ubuntu kernels.
BTW, it works fine on Debian kernels, for example on 4.16.0-2-amd64 I've tried supposed linux-oem-4.15.0-1006.9 but device node is still missing, although appears in /proc/tty/driver/serial $ uname -r 4.15.0-1006-oem $ sudo cat /proc/tty/driver/serial | grep -v unknown serinfo:1.0 driver revision: 4: uart:16550A mmio:0x7FFFF16000 irq:4 tx:0 rx:0 5: uart:16550A mmio:0x7FFFF14000 irq:5 tx:0 rx:0 RTS|CTS|DTR 6: uart:16550A mmio:0x280000000 irq:6 tx:0 rx:0 RTS|DTR 7: uart:16550A mmio:0x7FFFF12000 irq:7 tx:0 rx:0 CTS $ stat /dev/ttyS6 stat: cannot stat '/dev/ttyS6': No such file or directory -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux-oem in Ubuntu. https://bugs.launchpad.net/bugs/1769610 Title: Support Intel Atom (Baytrail-I) HS-UART serdev slaves over tty Status in linux-oem package in Ubuntu: Fix Released Status in linux-oem source package in Bionic: Fix Released Bug description: Support Intel Atom (Baytrail-I) HS-UART serdev slaves over tty On systems using Intel Atom (Baytrail-I) SoC's, slave devices connected on HSUART1/2 ports are described by the ACPI BIOS as virtual hardware using HID's INT3511/INT3512 [1]. As a consequence, HW manufacturers have complete freedom to install any devices on-board as long as they can be accessed over serial tty interface. Once such device is Dell Edge 3002 IoT Gateway which sports ZigBee & GPS devices on the HS-UART ports 1 & 2 respectively. Post 4.15, with CONFIG_SERIAL_DEV_BUS=y, serdev port controller driver handles the enumeration for the slaves connected on these ports. Also, /dev/ttySx device nodes for these ports are no longer exposed to the userspace. This driver has been submitted upstream and is under review. This issue has been identified as a regression in 4.15 and multiple solutions are being explored. Meanwhile, to support customer and maintain release schedule, this driver needs to be in Ubuntu 4.15 based kernels. The impact is limited to systems based on Intel Atom E38XX (Baytrail-I) SoC's. More info: https://marc.info/?t=152455871600007&r=1&w=2 Please don't triage, this bug is for tracking purposes only. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux-oem/+bug/1769610/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
