Booting Linux using UEFI can brick Samsung laptops

[GreyGeek]

http://www.h-online.com/open/news/it...s-1793958.html

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 affects300E5C, 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.

[GreyGeek]

And just like that a fix is issued!
http://www.h-online.com/open/news/it...l-1795332.html

[woodsmoke]

Samsung UEFI brick 10 - 30 - 13

http://scienceblogs.com/aardvarchaeo...t-our-problem/

One of the PC makers who sell Linux compatible computers is Samsung. That is, almost all of their machines can run Linux, and when it was discovered last January that some recent laptops cannot, it was universally seen as a bug.

dot, dot, dot. fast forward Oct 29 2013

The problem is known as the Samsung UEFI BIOS bug.

I won’t go into details I don’t understand: suffice to say that it has to do with the bootup sequence, where Samsung’s engineers have embraced the new UEFI technology without testing it sufficiently with Linux.

WOODSMOKE NOTE THIS SENTENCE -> -> -> The bug they inserted is pretty serious.

The Samsung UEFI BIOS bug disables a machine’s bootup firmware entirely if you boot Linux under certain circumstances. This renders the computer dead,

dot dot dot

I bought a Samsung NP535U3C laptop in July, immediately

WOODSMOKE - > - > installed the most recent version of Mint, the most widely used Linux distribution, and happily used my new machine for 3½ months.

YADA YADA YADA

Vendor says it is Samsung's problem, Samsung says not their problem and to ...." call Linux" about it.

comments?

woodsmoke

[GreyGeek]

Use the right kernel....
http://www.h-online.com/open/news/it...l-1795332.html

[SteveRiley]

This was all very well documented by Matthew Garrett:

http://mjg59.dreamwidth.org/22028.html
http://mjg59.dreamwidth.org/22855.html
http://mjg59.dreamwidth.org/23554.html
http://mjg59.dreamwidth.org/25091.html

I'm rather surprised that Samsung is acting ignorant of the problem, especially since it is provably a firmware bug that can be triggered even my mucking around with Windows.

[GreyGeek]

Wow, Steve. That last link is a stunner. To hobble a modern OS by the limitations of using a 64Kb volatile RAM is so unbelievably ludicrous one has to wonder if it was intentional, in order to block the use of Linux.

[SteveRiley]

To hobble a modern OS by the limitations of using a 64Kb volatile RAM is so unbelievably ludicrous one has to wonder if it was intentional, in order to block the use of Linux.

No, nothing so calculated as that. It's your basic cost-cutting of the hardware combined with sloppy programming of the firmware.

The bricking happens after installing a second OS and writing to the NVRAM. One could encounter this problem a number of ways on a pristine Samsung that's never had an OS:

* Installing Linux first, then installing Windows second
* Installing two Linux distros, each with its own NVRAM entry
* Installing Windows 7 and Windows 8, again each with its own NVRAM entry

UEFI should garbage-collect after every reboot. Samsung's doesn't. The right thing to do is acknowledge the bug, fix it, and push updates to customers. The absolute wrong thing to do is blame the user for installing Linux. But that's the easy and cheap way out, because the vast majority of people who trigger the bug will do so in this fashion. Disgusting, opportunistic laziness.