memory errors

By: Jörn Engel (joern.delete@this.purestorage.com), March 4, 2021 3:32 pm
Room: Moderated Discussions
Etienne Lorrain (etienne_lorrain.delete@this.yahoo.fr) on March 4, 2021 6:26 am wrote:
>
> Historically, I think ECC error detection was removed approximately at the time it took too much time to
> initialise the memory. At power-up, the parity bit is not initialised: if you dump the DDR before initialisation
> you get mostly zero bits but you will also get bits set (I do not know why the capacitor is still charged
> at power-up). If you do a quick power-cycle, it is obvious you will still have bits set.
> When the memory of the PC increased to few tens of megabytes, the CPU (at that time) was
> not able to clear that DRAM (so initialise the ECC) in less than 10 seconds, and the PC never
> had a powerful DMA to do such work. To cut boot time, they removed the parity bit.

Or you could not bother clearing memory. BIOS/Bootloaders need to initialize however much they use, the kernel needs to keep a bit per page to indicate whether memory has been cleared before and lazily do the work as memory gets allocated. We did that in a past project. It has the added benefit that you can leave crash dumps in RAM and retrieve them after reboot.
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TopicPosted ByDate
CPU & Memory bit flipsGanon2021/03/03 09:05 AM
  Also "Silent Data Corruption"Adrian2021/03/03 10:42 AM
    Thanks for the referenceGanon2021/03/03 11:47 AM
  Implications for linux page cacheanon2021/03/03 11:54 AM
    Implications for linux page cacheLinus Torvalds2021/03/03 01:54 PM
      memory errorsblaine2021/03/03 02:53 PM
        memory errorsanon22021/03/03 05:30 PM
          memory errorsdmcq2021/03/04 05:16 AM
            memory errorsEtienne Lorrain2021/03/04 06:26 AM
              memory errorsdmcq2021/03/04 06:40 AM
                memory errorsEtienne Lorrain2021/03/04 06:58 AM
                  memory errorsdmcq2021/03/04 07:12 AM
                  memory errorsCarson2021/03/05 02:31 AM
                    memory errorsEtienne Lorrain2021/03/05 06:23 AM
                      memory errorsrwessel2021/03/05 07:48 AM
                      memory errorsdmcq2021/03/05 12:01 PM
                        memory errorsrwessel2021/03/05 12:23 PM
                          memory errorsdmcq2021/03/05 12:51 PM
                      memory errorsBrendan2021/03/05 11:38 PM
                      memory errorsCarson2021/03/06 01:35 AM
                        memory errorsCarson2021/03/06 06:24 AM
                memory errorsDavid Hess2021/03/04 01:44 PM
                  memory errorsrwessel2021/03/04 05:14 PM
                  memory errorsLinus Torvalds2021/03/04 08:21 PM
                    memory errorsanon22021/03/04 09:46 PM
                      memory errorsCarson2021/03/05 02:43 AM
                        memory errorsanon22021/03/05 07:55 AM
                    memory errorsgallier22021/03/05 02:22 AM
                  memory errorsdmcq2021/03/05 12:59 PM
                    memory errorsDavid Hess2021/03/06 04:27 AM
                      memory errorsCarson2021/03/06 06:44 AM
                      memory errorsGabriele Svelto2021/03/06 10:11 AM
                        memory errorsDavid Hess2021/03/06 10:28 AM
                          memory errorsMichael S2021/03/06 02:45 PM
              memory errorsDoug S2021/03/04 10:48 AM
                memory errorsMichael S2021/03/04 11:36 AM
              memory errorsJörn Engel2021/03/04 03:32 PM
                memory errorsLinus Torvalds2021/03/04 08:47 PM
                  memory errorsEtienne Lorrain2021/03/05 01:09 AM
                  memory errorsMichael S2021/03/05 04:06 AM
                    memory errorsLinus Torvalds2021/03/05 11:59 AM
                      memory errorsrwessel2021/03/05 12:32 PM
                        memory errorsrwessel2021/03/05 12:37 PM
                        memory errorszArchJon2021/03/06 08:39 PM
                      memory errorsGabriele Svelto2021/03/06 12:58 PM
                  memory errorsJörn Engel2021/03/05 10:12 AM
                Amiga recoverable RAM disk?Carson2021/03/05 03:03 AM
                  Thanks - TIL a cool Amiga feature (nt) (NT)John2021/03/05 12:51 PM
                    Another cool Amiga feature, datatypesCharles2021/03/06 12:01 AM
                      Another cool Amiga feature, datatypesJukka Larja2021/03/06 01:23 AM
                      Another cool Amiga feature, datatypesAnon2021/03/06 12:40 PM
                      Another cool Amiga feature, filesystemsMarcus2021/03/07 12:28 AM
  CPU & Memory bit flipszArchJon2021/03/04 06:39 AM
    CPU & Memory bit flipsdmcq2021/03/04 06:59 AM
      CPU & Memory bit flipsrwessel2021/03/04 12:27 PM
  speak of the devilRobert Williams2021/03/05 07:53 AM
    speak of the devildmcq2021/03/05 11:26 AM
      speak of the devilRobert Williams2021/03/05 03:15 PM
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