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Thread: nvram, nvram_x

  1. #1

    Lightbulb nvram, nvram_x

    Hi,

    Here is my problem:

    I configure WL-500g for with my setting (start dropbear after boot, some iptables mods...etc)

    then i save my config via web interface.

    When I try to restore config after reseting wl-500g, bootCmd, and dss entry wasn't in my nvram (nvram show|more)
    When i config file, dss and bootCmd entries was there.

    i try to config manualy again, and save with nvram_x fget,
    and restore with nvram_x fset....The same result

    But when i create entry something like 9_x_bootCmd, and save config with web, or nvram_x, resotration work fine.(but bootCmd doesn't work of course)

    Am I doing something wrong, or this is bug???
    Could someone take a look at this.

    I use FW 1.6.5.3-5

    Thanks a lot
    Last edited by pipos; 05-04-2004 at 23:13.

  2. #2
    Join Date
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    Why you're trying to use nvram_x instead of nvram? Yes, there is a real difference between them in way how they treat variable names, so 9_x_bootCmd will never work, because rc.nvram does not expect this.

  3. #3
    I need to make complete backup of my settings from nvram.
    And when I restore it, all settings are restored except bootCmd and dss entries.

    I don't know why at this time.

  4. #4

    Getting rid of NVRAM?

    I though the nvram binary was accessing /dev/mtd/4, basically like flashfs, but it turns out that it uses /dev/nvram. Looking at the nvram_linux.c code on both user and kernel side, I do not quite understand what's going on.
    E.g. it seems the nvram size is 32KB, but the nvram partition is 64KB.
    Where did the factor of 2 go?

    Does anybody know if the nvram is used by something else than /usr/lib/libnvram.so? I'm thinking of merging the flashfs and nvram partitions into a 128KB jffs2 partition and reimplement libnvram.so to store its data in a plain old filesystem.

  5. #5
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    64k is just the page size of some flashes. You cant remove nvram completely - pmon uses it to boot linux.

  6. #6

    NVRAM lifetime

    I'm currently implementing a system based on the WL500g platform and I'd like to store some data, preferably surviving power-offs. So NVRAM is the thing to use, and it works. However, I know that NVRAM can be flash-like memory that has a limited lifetime, related to the number of writes. Does anybody know what kind of memory is used as NVRAM in the WL500g?

    I'm thinking of using files in /tmp and only use NVRAM as a backup to store data less frequently. But maybe this is not necessary?

  7. #7
    Join Date
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    Hi

    Since NVRAM resists inside the Flash Memory it has some 1000 write cycles. This is enough for normal configuration files which are not changes more than every some days, you can calculate it for yourself how long it will survive .
    Modern ones like in the 500g have a guranteed 10000 cycles lifetime, mostly much more since thy gurantee it over the complete temperature range which is normaly not used in home envoirements (+85°C).

    Greets
    My Stuff: WL-500g, Mapower H31x 10GB HD, Philips Webcam Vesta PRO, TerraTec Webcam PRO, USB Hub

  8. #8
    Thanks alot

  9. #9
    Join Date
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    Hehe, what are you developing ?
    I´m just curious
    My Stuff: WL-500g, Mapower H31x 10GB HD, Philips Webcam Vesta PRO, TerraTec Webcam PRO, USB Hub

  10. #10
    Unfortunately I cannot tell you. Company secret

  11. #11
    Join Date
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    Question

    Quote Originally Posted by Exirion
    Unfortunately I cannot tell you. Company secret
    Thought a forum like this was meant to help each other and share information and knowledge.
    Brubber

    WL-500g, WL-138g, WL-160g

  12. #12
    Quote Originally Posted by brubber
    Thought a forum like this was meant to help each other and share information and knowledge.
    What I'm doing with the WL500g is completely irrelevant for other people. I asked something about NVRAM, got a reply, and that might be valuable info for other people as well. That's what counts.

  13. #13
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    Quote Originally Posted by Exirion
    What I'm doing with the WL500g is completely irrelevant for other people. I asked something about NVRAM, got a reply, and that might be valuable info for other people as well. That's what counts.
    Strictly speaking: you can't be the judge of that

  14. #14
    Join Date
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    Getting back on topic.

    Just wondering, what is the ASUS definition of NVRAM?

    AFAIK NVRAM is battery backed up SRAM or in a less strict definition also a CMOS or an EEPROM
    Brubber

    WL-500g, WL-138g, WL-160g

  15. #15
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    NVRAM stands for Non Volatile Random Access Memory. So it can be a lot of different types of memory as long as its non-volatile and random access. This includes battery backed SRAM and harddisks as well.

    The NVRAM in the Asus WL-500g is a seperate section of the flash space available. 32k is used and the page size is 64k.

    Info: http://wl500g.info/showthread.php?t=809

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