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The Curse of Soldered RAM

blog.hardill.me.uk103 points119 comments
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A Lenovo X1 Carbon that had been reliable for years began crashing browser tabs and remounting its root filesystem read-only, with Btrfs reporting data checksum failures. A Memtest86+ boot test quickly confirmed faulty physical memory. On a laptop with replaceable memory, the usual fix would be to identify and swap the bad DIMM; on this machine, the RAM is soldered to the motherboard, making repair impractical without specialist chip-replacement skills. The experience frames soldered RAM as a costly, anti-repair design choice: a still-capable computer may need replacing because one component has failed, a concern amplified by high memory prices.

To keep the laptop usable temporarily, the author used Linux’s built-in memmap option to prevent the kernel from allocating the defective memory ranges. Fedora does not normally include badram, an alternative requiring an out-of-tree kernel patch. Memtest86+ can provide the needed address ranges, but exporting them from the Ventoy boot setup failed, so they had to be copied manually. Putting the long list directly in Fedora’s GRUB configuration caused dollar signs in the values to be expanded incorrectly; saving the list as a GRUB environment variable and referencing it from the kernel command line allowed the system to boot with the exclusions applied. This is a stopgap, not a repair: the author plans to back up important files, investigate the filesystem damage, and replace the laptop.

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