Writing a Bootloader

Re:Writing a Bootloader by aidos on Friday October 20, 2017 @05:29PM (#15519228)

I love this comment, in part because it's totally outside my area of knowledge but I can still picture the battles and dead ends you must have worked through to make it stable.

Did you kill a lot of hardware figuring it out? What was the purpose of poking that caused the underlying issue?

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Re:Writing a Bootloader by mjg59 on Saturday October 21, 2017 @04:04AM (#15521115)

I only killed one laptop in the end, the rest of the testing was done with VMs and a system that had a hardware EFI variable reset button. The issue that was triggering it on Samsungs was the driver that supported backlight control - it worked by writing a value to an address which triggered some system management mode code in the firmware, but that code only worked properly in BIOS mode. In EFI mode it generated machine check exceptions, which in turn caused the kernel to dump the backtrace to EFI variables.

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Re:Writing a Bootloader by exikyut on Saturday October 21, 2017 @07:57AM (#15521584)

> a system that had a hardware EFI variable reset button

Ooh, that sounds useful for hardware hackers. What was this?

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