On 11/02/2019 18:27, Marc Gonzalez wrote: > A colleague pointed out that some memory areas are reserved downstream. > Perhaps the FW goes haywire once the kernel touches reserved memory? Bingo! FW quirk. https://patchwork.kernel.org/patch/10808173/ Once the reserved memory range is extended, I am finally able to read large partitions: # dd if=/dev/sda of=/dev/null bs=1M 55256+0 records in 55256+0 records out 57940115456 bytes (58 GB, 54 GiB) copied, 786.165 s, 73.7 MB/s Thanks to everyone who provided suggestions and guidance. Regards.