Technically minded Weblog

Decided to do some more router hacking on my F7D3402.

Got sick of DD-WRT on my F7D3402 (due to it’s outdated kernel and because I could not use my USB WiFi dongle, because I couldn’t build the needed drivers, again due to outdated kernel), decided to ditch it and install OpenWrt instead.
OpenWrt seems to support BCM4718 chip, so this should not be a big problem. Current release in SVN trunk (which I will be using) uses Linux 3.3.7 which is a recent version. Nice. (see Update 1)

Patched the kernel (needed due to Belkin’s nonstandard TRX magic):
/drivers/mtd/maps/bcm47xx-flash.c -> change TRX_MAGIC to 00017517
/drivers/mtd/bcm47xxpart.c -> change TRX_MAGIC to 00017517

Now it boots (at least I can see it booting). But it does not mount root. It seems that it does not like Belkin’s mksquashfs 3.0 (perhaps it’s too old), because it sees the flash partitions, but does not mount anything.
Will try to rebuild with mksquashfs 4.2 instead.
Also, it tries to use JFFS2, would be nice if that worked as we could install OpenWrt packages (we can still use Optware though, even without JFFS2).

Will try to rebuild again and update this post.
When it’s done, will upload the TRX binary here in case if anyone needs it.

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Update 1: It boots but nothing works, except the shell and USB. No Wifi or LAN. It seems that OpenWrt still does not fully support the BCM4718 chipset.

Update 2: I won’t be messing with this, it’s not yet usable. Switching back to DD-WRT for now. Will probably buy a more decent device to mess with in near future.

I was given a PC for repair with one major problem: it does not turn on at all, not even fans spin.
The reason of failure was likely a bad PSU. The owner told me that when they tried to turn it on, the PSU went boom.
I have opened the PSU (Branded “ISO”, a Channel Well budget series. They are OK PSUs except for capacitors) and found 2 bad capacitors (the infamous F*u branded capacitors). The PSU still sort-of worked (5Vsby was 5.24V) but it whistled badly when powered up (didn’t try jump-starting it).

I have installed by bench supply (a 350W FSP) and tried to power the system on, it was dead.
Then I started examining other components. Removed the processor and installed it back, checked RAM.
Then, out of curiosity, tried to turn it on again and it worked ! Booted to XP without problems.
I thought “OK, it looks like only the PSU bit the dust, the itself system is fine” and bought a new PSU (400W FSP).

Installed this PSU to the system and tried turning the system on and… it wad dead. WTF ?!!?!??
Again, checked cables, components, tried clearing CMOS, tried my bench PSU again. Nothing. The system was stone-dead.
(I did manage to get the system to at least try to turn on once, but it turned itself off after a few seconds).
Well, it seems that the old PSU did damage something when it exploded…

The happy part for me is that the owner decided to give away the system to me (for parts) at the cost of recovering information from the hard drive.

System specs (from memory, too lazy to look up):
MB: Gigabyte, Socket AM2
CPU: Some AMD Athlon 64 (single core)
RAM: 2x512MB (1GB)
VGA: GeForce 7400 or 7600 PCI-E
HDD: 250GB Samsung SATA (in perfect condition)
Also, some optical drive and a generic black mid-tower case.

HDD went to my NAS (a hacked F7D3402, mentioned in the previous post, had to do some mods so that the HDDs would mount properly when connected to USB Hub, but thats a different story), other parts are still in the case.

Lesson learnt: Avoid cheap PSUs. Always remember to check your PSU from time to time. If it whistles or makes any unusual sounds (eg. whine), you should stop using it, unless you know the PSU should behave like that (my new Corsair TX850 V2 did whistle on standby when it was new, but stopped whistling after some time).
A bad PSU can take the rest of your system with it when it dies !

P.S.: I had another system brought to me for an upgrade (a LGA775 based PC with 2.8Ghz Celeron D and 512MB RAM with XP on it, upgaded to a 3.4 Ghz P4, 1GB RAM and Windows 7)
Before upgrading, I decided to check the PSU, as it looked very much like one of those generic chinese cheapies (even though it had “Q-tec, The Netherlands” on the label), and, surely enough, found a bad capacitor in it (again, one of these damn F*u caps). Replaced this PSU with a 400W FSP (mentioned earlier).

Enough for now…

Need to clear my news buffer.

Built and sold a PC.
Too lazy to write full specs, but it’s based on a quad core Athlon 2, 4GB RAM and HD4670 video.

Also got some new hardware:
Bought a new MP3 player (an old stock Sandisk Sansa Fuze) to replace my previous one (also a Sandisk, with a broken dock connector (the cable is fine though)).
Installed Rockbox on it. Everything works fine. Too bad the battery life is kinda low for a new player. Maybe because it’s old stock.
Also bought a Wireless N USB stick. It works fine (even has an antenna). It is a rebranded (TP-LINK) Atheros Wireless N USB stick based on AR9271 chipset.
It works fine but driver installer does not install Atheros wireless extension DLL (athext.dll) which is required for automatic wireless configuration after a system restart.
I have to disable and enable (or unplug and re-plug) the wireless adapter for it to work again after a restart.

Also, got an Acer laptop for repair. Bad video card, a GeForce 8600M GS.
Red stripes in BIOS during boot. Windows boots and runs fine until I install the video card drivers.
After that, in Windows 7 the system freezes on Windows logo while booting, in XP I get a corrupted BSOD after the Windows logo and the system restarts.
The drivers are fine as the system worked fine with the same drivers before.
The good thing that the card is a MXM (Mobile PCI Express Module), so it should be replaceable.
Now I need to find a compatible MXM card to replace the dead card with.

My 8800GTX in my main system also seems to have a potentially bad GPU. But it’s well cooled and is running fine for 3 years already so it should be fine until I decide to upgrade the video card.

That’s all for now.

I’ve recently replaced my virtual server with a physical machine.
I’ve used an old Pentium 3 PC as a server. It cost me nothing to build because I already had all the needed parts in my junk pile.
Now, the specs:
CPU: P3 1 GHz cD0
MB: Intel Easton (D815EEA, i815 based)
RAM: 512MB (2×128,1×256)
HDD: 40GB Samsung
CD/DVD: an old LiteOn DVD burner
LAN: 4 NICs (2 in use).
PSU: 230W Hipro
OS: Win2003

The new server does everything my virtual server did (DNS, DHCP, Torrents) plus it also serves as a IPTV to HTTP proxy (like udpxy, I’ve previously used, or, if exactly, tried to use). This also solves my IPTV problem. The new server runs fine. It could use more RAM though, as it only has 512MB and often runs out of memory. Too bad, i815 only supports 512MB (Intel did this because some older P3s were actually better than early P4s).

But I’ve recently (in fact, while writing this post) experienced some strange issues with IPTV connections dropping. I wonder if this is related to the proxy software, server itself, or it’s just a bad IPTV signal (happens sometimes too).
(the error message in IPTV proxy’s logs said something about too many dropped packets).

Will update, when I will have more news.

Bought some new hardware for my secondary PC.
Installed additional 2 TB (a Samsung HD204UI) hard drive and replaced 2x1GB (so 2GB) Kingston RAM with 2x2GB (4GB) Kingston RAM.
Old 2x1GB modules went back to my primary system, from which they were removed about a year ago.

Hard drive is working fine so far. Shows 1.86 TB in Windows.
RAM is a different story. No, the RAM modules are OK, but my 32 bit Windows (Windows 7 to be exact) only shows 3.25GB of RAM instead of 4GB.

Because it would be too much work to reinstall all my stuff on 64 bit OS, I’ve decided to Google for a solution on how make all of my 4 GB RAM usable in 32 bit Windows.
And I have found it. I have found a kernel patch which allows 32 bit Windows to use more than 4 GB RAM.
In fact, even Microsoft themselves have admitted that 32 bit Windows can use more than 4 GB RAM when using PAE (Physical Address Extension) but they artificially limited the maximum amount of memory in 32 bit client systems to 4GB. 32 bit server systems can support up to 128 GB.

I won’t post the patch here. You can find it by googling for “windows pae patch wj32”. Patches are available for Vista and 7.
Be warned that this is a kernel patch. Use with caution.

It turned out that the software I wanted to use to redirect IPTV traffic does not work as expected. Some packets are dropped due to insufficient cache size (which is only 64KB) resulting corrupted video. There was an option to change the cache size but it did not work. The version of UDPXY I’m using cannot sustain re-broadcasting a 4.5Mbit/s stream through HTTP without corruption. I need to significantly increase the minimum cache size. This can be done only by recompiling the application. I can recompile UDPXY from the sources on the router directly but I need to install Optware and the development tools. They can only be installed in a SD card or a network share. Because my router does not have an SD card mod, network drive is the only option.
But the problem is that Windows LANMAN Server (the one used to host network shares) drops connections too often, resulting in failed installations.
So far I’ve been able to install Optware, but was not able to successfully install the development tools yet.
In case I won’t find a way to install the dev tools on the router, I guess I’ll have to use Linux running in a VM to cross-compile UDPXY and then upload it to the router.
Will post when I will have more news.

I have a Linksys WRT150N router running DD-WRT (Linux based router OS, original Linksys OS was crap). Because my ISP uses separate networks for IPTV and Internet, I had to connect IPTV network cable to a LAN port on my router for IPTV to work. But that created a major problem. My wireless and LAN was constantly being flooded with IPTV multicast data (at ~4.5Mbits), regardless if the IPTV player program on my PC was running or not.
This flood of IPTV data rendered my Wireless network useless because it could not serve the Internet properly due to being constantly flooded with data (it was nearly impossible to connect and the speed was < 10KB/s).
I’ve found a solution on Google. It suggested creating separate VLANs (Virtual LANs) for IPTV and the rest of the network, thus separating IPTV port from the rest of the network, and redirecting data from IPTV port to the rest of the network through HTTP.

I thought I would create a separate VLAN for IPTV . But on DD-WRT site, they say that my router does not support VLAN.
But when searching the forums I’ve found out that my router does indeed support VLAN (I have a newer hardware revision), but I need to update to the latest SVN (subversion) build of DD-WRT and I need to enable VLAN function from the shell.
I’ve successfully created two separate VLANs, one for IPTV port and one for all other ports and blocked multicast data from going outside IPTV VLAN.
I’ve loaded udpxy to my router to forward IPTV data from IPTV VLAN to main VLAN through http.
Now when I watch TV on my PC, IPTV data only goes to the PC on which I’m watching TV.
Now my wireless and LAN is no longer being flooded with IPTV data. I guess wireless should now work fine too, but I have no laptop or a working wireless card to test it.