Can setting 32 megs on a 16 meg shipped router cause instability?

Discussion in 'Tomato Firmware' started by Sunspark, Nov 23, 2007.

  1. Sunspark

    Sunspark LI Guru Member

    Hi just wondering. Occassionally I will have the oddest lockup in Tomato where the router simply stops working (1 time was a half-crash with kernel panic in the log). The wireless & wan goes down, and I can't connect via ethernet cable either.. yet plugging in the cable does light the LED up.. All I can do is power cycle it, and then it's fine again.. of course there are no logs so I have no idea what happened.

    My WR850G router was shipped with 16 megs of ram by default, but I looked at the board and it's got 32 megs of ram on it. (16 megs on the top side.. probably another 16 meg chip on the bottom also).

    Basically what I am wondering is, are there any circumstances when even though you have the chips you might not want to set 32 megs?

    Today I performed a full nvram erase, and left it at 16 megs for now.
  2. Disman_ca

    Disman_ca Super Moderator Staff Member Member

  3. szfong

    szfong Network Guru Member

    I also have one of such a router, it's a wrt54g v2, early model xh/xb revision. 4MB flash/32MB ram. It ran stable for years using 4/16 configuration. 4 commands were issued to enable it:

    nvram set sdram_init=0x008
    nvram set sdram_ncdl=0x000
    nvram commit

    However, UNDER NO CIRCUMSTANCE should they EVER BE ISSUED on a non-xh/xb revision (You WILL BRICK IT!!!! and ALSO check the memory chips to make sure they are indeed two 16MB ram chips).

    30s reset will drop it back to 16MB ram. update the CFE to permanently enable it. CFE updating should be done using jtag interface, although I've done it a couple dozen times without the jtag cable (modified openwrt firmware).

    You need to open the router and carefully examine it!

  4. Sunspark

    Sunspark LI Guru Member

    Those nvram commands are the same ones I used. It seems unlikely that 1 side would have a 16 meg chip and the other side 8. I only looked at 1 side of the circuit board, so I am pretty sure it has 32 megs. It's run fine set as 32 for awhile now.. Just, every once in awhile it'll get this very odd total router freeze-lockup which I cannot explain so I was wondering if it was ram related, or maybe something else.
  5. szfong

    szfong Network Guru Member

    If you get this total freeze-up with tomato, try flashing with thibor or dd-wrt, run it for awhile, if you also get this lockup-freeze, then it's hardware-related, time to get a new router. My bcm4712 based wrt54g v2 rev:xh will perform random reboots. setting it in client bridge eliminated such reboots (driver issue). newest dd-wrt runs very reliable on this old router without random reboots. Tomato run EXTREMELY well on the newer wrt54gl and buffalo routers. uptime can be several months until a power outage.
  6. szfong

    szfong Network Guru Member

    Sunspark, I forgot to mention that yes, latest tomato on bcm471x is un-reliable. I get random reboots on two of them, a v1.1 (4/16MB) and a v2 (4/32MB). The two bcm471x has been flashed with latest dd-wrt v24 rc-5, as it is more reliable (higher uptime) because dd-wrt uses newer wl drivers which fixes some issues with older hardware. However, bcm5352 under tomato is VERY reliable. I can get months of uptime. I believe the increased memory has no effect on reliability. However, even under tomato, cpu usage is a bit higher on the bcm471x-based routers, compared to the bcm5352. Routing performance is also reduced.

  7. Maggard

    Maggard LI Guru Member

    To add another datapoint, I've a WRT54GS with 32MB RAM, out of the box, and it's never had a lockup. This was true under Sveasoft and now under Tomato.
  8. Sunspark

    Sunspark LI Guru Member

    True.. I'm inclined to think it's what szfong said. It will be interesting to try the x-wrt w/ kamikaze when they have a 2.6 kernel broadcom driver and the interface is finished.
    I do wonder though why Tomato is not using the newest wl driver if there is one that works better on the older cpus.
  9. szfong

    szfong Network Guru Member

    Maggard, I believe wrt54gs v3-v6, wrt54g v4-v6, and all wrt54gl uses the newer bcm5352 chips, they should run reliable as heck under tomato. Do you have a v3, I believe it was the last version that had 32MB ram and a bcm5352.

    Sunspark, most of tomato uses/based upon the latest linksys wrt54gl source and driver codes (WRT54GL_v4.30.11_US.tgz according to the tomato sources). Since all wrt54gl uses bcm5352 chip, it should run very reliably, as does the buffalo routers. It's these bcm471x chips that is a pain in the neck (low uptimes). The newer bcm5354 are even less compatible.

    I've since decided to use the newest dd-wrt or tofu's older firmware on the bcm471x routers and all of my bcm5352 uses tomato or dd-wrt. X-wrt has had this issue fixed quite awhile ago.

    Check the to find out what chip is in which of your routers.

  10. Maggard

    Maggard LI Guru Member

    I've a CGN1, WRT54GS v.1, which according to the very complete Wikipedia is an ADMtek 6996L chipset at 200MHz with 32MB/8MB RAM.

    Runs Tomato flawlessly, except for a minor login issue with my Samsung T409 phone.
  11. szfong

    szfong Network Guru Member

    I guess you do have a bcm4712 chip, the amd6996l is the switch chip. Later revision used the BCM5325 switch chip while bcm5352 has it built-in. How many days is your uptime?

    I only get months of uptime from the bcm5352 chip based routers with tomato. only x-wrt & dd-wrt do I get over a month of upime on these older routers.
  12. Maggard

    Maggard LI Guru Member

    Probably the longest uptime has been 90 days.

    I unplug the router to dust, to rearrange cabling, or when I'm going to be away for an extended period and won't be remoting in. Also when there's a reason to update the firmware (usually every 2nd or 3rd release there's enough new goodness to inspire me to update.)

    After, hmm, probably 4 or 5 years this router has done a fantastic, trouble-free, job.
  13. szfong

    szfong Network Guru Member

    Good to know... massive wireless traffic with bcm4712+tomato will cause the two remaining routers I have to randomely reboot. The half dozen buffalo's and wrt54gl I have are extremely stable, never randomly reboots or needs any sort of maintenance. I now have several bcm5354 routers, they run at 240MHz and cheap as heck. About $25 after rebates. I just wish tomato will work on them. They've already been upgraded to dd-wrt, so reflashing to tomato would be easy if it is ever updated to support the newer chip. Wan-lan speed is more than twice as fast as my older bcm4712 routers and half the price!
  14. Sunspark

    Sunspark LI Guru Member


    So today was experimentation day. I flashed in White Russian to check it out. I could NOT STAND IT. The interface is SLOW. And on top of that, I like to erase nvram, and White Russian does not like that. You can do it, but then your nvram is empty and it only starts to repopulate it as you click and save on everything one by one. Maddening and too time consuming. At least Tomato loads up a bunch of defaults ready to go!

    So I went back to Tomato.

    Then I decided hmm, oh what the heck, let's try 216 mhz to see what happens. But no matter what, It would be 250 bogos.. So I tried 228 instead, zap! BRICK.

    I don't have a jtag cable or anything, so it looks like I'm going to have to trot out and get a 54GL after all. At least it'll supposedly be more stable. I wouldn't mind an N device but DSL is not faster than G. I won't throw out the 850G, I'll try to figure out how to debrick it sometime after having tried like crazy with tftp.

    So the lesson here is, WR850G, your crystals will only let you do 200 or 250 afaik. Oh well.
  15. szfong

    szfong Network Guru Member

    If you get a new N router, get one with gigbit ports. I avoid overclocking, but I played around it for awhile. You need jtag cables to unrick it, BUT you can modify the bootloader so as to easily unbrick it. In the future, if you play with overclocking, modify the bootloader so as to allow easy recovery by following the info in the wiki. You should enable boot_wait, and reset_gpio. It makes life easier.
  16. mstombs

    mstombs Network Guru Member

    It makes sense there is a broadcom chip in those early routers, but most wikis seem to copy the linksysinfo one and refers to the switch as the chipset - is there an authoritative guide you can refer to so the FAQ can be updated?

    Are these reference to chipset correct?
  17. Disman_ca

    Disman_ca Super Moderator Staff Member Member

    Originally when Linksys was making the WRT54G the switching chip was not on the Broadcom chip. In other words, the switch chip was separate. Later on they started using a Broadcom chip with the switching chip on board.
  18. szfong

    szfong Network Guru Member


    The has a pretty accurate, well updated list:
    They are one of the best sources!

    Or, I use a "lighted" magnifier and razor to remove labels, on the board to be sure.
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