Booting Linux using UEFI can brick Samsung laptops - The H Open: News and Features

Booting Linux using UEFI just once on various Samsung laptops is enough to permanently stop them working. Several reports have been posted on the Ubuntu bug tracker, but the problem is likely to also be present in other Linux distributions, as it appears to be caused by a kernel driver for Samsung laptops. Kernel developers are currently discussing a change which would disable the driver when booting via UEFI.

Ubuntu developers were informed of the problem by one user last year, after he had tried to UEFI boot Ubuntu 12.04 or 12.04.1 on a Samsung 530U3C live from a USB flash drive. He had prepared the drive with Ubuntu's Startup Disk Creator, which sets everything up for booting via BIOS or EFI. Ubuntu froze shortly after loading the kernel and the user then powered down by holding down the power button. Thereafter the laptop refused to boot and the firmware would not even show basic startup information. Samsung repaired the laptop, which was under warranty, by replacing the motherboard. When the same thing occurred with the repaired machine, the user alerted the Ubuntu development team.

Since then, many more users have reported having bricked their laptops by trying to boot Linux. The problem also appears to affect Ubuntu 12.10 and other Samsung models. The Ubuntu bug report includes posts from users reporting that the problem also affects 300E5C, NP700Z5C, NP700Z7C and NP900X4C series laptops. It does, however, only occur when Linux is booted using UEFI. It does not appear to matter whether Secure Boot is on or off. The problem can be circumvented by booting Linux using the Compatibility Support Module (CSM). UEFI firmware on many recent systems includes a CSM to enable operating systems to be booted in the same way as on computers with conventional BIOS firmware. Installing Linux alongside a Windows installation installed using UEFI mode is, however, not straightforward when booting using CSM.

The Ubuntu development team has held talks with Samsung staff, who have identified the kernel's samsung-laptop driver as the prime suspect. This driver has previously had issues – it had caused problems for other Samsung laptop owners when booting Linux using UEFI. Also involved in analysing the problem is Intel developer Matt Fleming, who posted two kernel changes for discussion a week ago. Since one of them ensures that the Samsung driver is not activated if Linux is started using UEFI, this should resolve the problem. It appears at present that this should be sufficient to prevent damage to Samsung laptops; however, these two patches have yet to be merged into either the main Linux development tree or recently released stable and long-term kernels 3.0.61, 3.4.28 and 3.7.5.

According to Canonical's Steve Langasek, Samsung developers have been attempting to develop a firmware update to prevent the problem for several weeks. Langasek is advising users to start Ubuntu installation on Samsung notebooks from an up-to-date daily image, in which the Ubuntu development team has taken precautions to prevent the problem from arising. It is, however, not completely clear that these measures are sufficient. In addition to the samsung-laptop driver bug, there may be, it appears, other ways of messing up the hardware and firmware on some Samsung laptops to the extent that they will no longer boot.

(djwm)