Installing Debian on Agestar without serial port

I have prepared a firmware and tutorial to Install Debian here, this time without the need for serial port. I have tested this, and it seems that everything works. But of course I will not be responsible if anything happens. If you think there are some missing, unclear or inaccurate steps, or if you doubt about something, then don’t install it. If you have anything to ask just email to yohanes [at], or just post your questions as comments.

NOTE: the web update method only works on agestar ncb3ast, other models can work by using serial port and latest patch for kernel source (2.6.29 or later).

Reverse Engineering Linux Kernel Image and Modules

I have switched my mind from doing the kernel porting to some other activities, which is reverse engineering ARM binaries for Symbian platform. When just starting, I thought to my self: why don’t I try to reverse engineer the original Agestar firmware, and may be I can complete some drivers for STAR STR9100. So I did, and I can get the watchdog function to work (at least I think it works).

zImage and bootpImage are compressed kernel image, this is compressed by using GZip method 8. The easiest way to decompress it is to give it to gunzip. I just searched the kernel image for the sequence 1f 8b 08, and cut it using khexedit. You don’t have to find where the compressed data ends, gunzip will ignore trailing garbage.

Continue reading “Reverse Engineering Linux Kernel Image and Modules”

How many of you are using STAR 9100 based NAS?

As listed on one of my previous posting, STAR 9100 (to be precise STAR 9104) is being used in these devices:

Coolmax CN-570
Emprex NSD-100
Agestar NCB3AHT
revoltec rs049

We can see from the boot log that says the machine is STAR_STR9100. Lately I have worked less and less on this device, because it has been running smoothly enough for me (I have run it continuously for a week). The last few parts is not so important for me. These four parts are RTC (turns out to be a very limited RTC), LED (only one LED inside the box, which is not very useful), and button (I have never used the button anyway), and Watch dog (this one might be useful, but I don’t have any documentation about this).

I am planning to stop further development. I was planning to build a custom firmware, but I think a full Debian distro is much better for me. But, if there are quite many people that uses this devices and are expecting something like NSLU2 (easy installer, etc), then I might continue the development. So, If you are using Agestar or agestar like devices, please leave a comment, and let me know what you expect.

If I am going to continue the development, I will need to buy another box, because I am currently using this one extensively for my daily activities. Irina (that is the name I gave to my NAS box) is now serving MP3, serving web page, and act as a download station.

RTC on STR9100

I have spent many hours to work on the RTC part, and I decided to give up for now. I have been able to activate the clock, set the clock, and make it run. But the RTC is not useful. First, it is not battery backed, so when you turn off your device, it will not keep the time. Second, it can store only the seconds, minutes, hours, and day of the month. The problem of not having a documentation is sometimes you get stuck, and don’t know what to try next.

There is one feature that is supposed to be useful if I can make it work: the alarm capability. With alarm, some cron-like applications can set to be notified when a particular time comes (it will ease the CPU burden). As far as I know, the cron daemon doesn’t use this feature, so it is not a great loss.

There is one thing that still puzzles me. The original firmware uses X1205 through an I2C bus. From my understanding, the X1205 have different abilities compared to the STR9100 RTC. So I don’t know whether there is actually another RTC on the board.

Since the RTC is not very useful. I will let go hacking this part until I find other clues.

Here is the output of the original firmware.

X1205: I2C based RTC driver.
i2c-core.o: driver X1205 registered.
X1205: found X1205 on STR9100 I2C Adapter
ccr_write_enable: verify SR failed
i2c-core.o: client [X1205] registered to adapter [STR9100 I2C Adapter](pos. 0).
X1205: i2c_add_driver RTC driver.
X1205: misc_register RTC driver.

LED driver

I was very tired lately because I have to do many other things beside hacking the agestar kernel. So when I have time this morning, I decided to work on the easiest part on my list: LED driver. Agestar NCB3AST only have one controllable led, inside the casing, so I don’t know how useful this is (I think you can peek a little bit when the casing is closed). The LED and LCD display front is actually controlled by different unit, not controllable by CPU. Because this part is not important, I decided to upload the patch later.

Right now I am starting to look at the RTC driver. Hopefully this one will be more useful.

Network Driver Problem Solved

I ported STAR 9100 network driver without a documentation, I just blindly use the old driver and modify it to fit with all of the changes in the networking stuff since kernel 2.4.27. The driver claims to support scatter/gather I/O, but there is no implementation of scatter gather I/O in the hard_start_xmit function. I don’t know whether this device supports it or not, so I just change this line:

dev->features |= NETIF_F_SG|NETIF_F_IP_CSUM

to this:

dev->features |= NETIF_F_IP_CSUM

And now the sendfile function works (although it would be faster if the driver supports scatter/gather IO).

My Network driver is buggy, sendfile() syscall doesn’t work

I have concluded the source of failure for many applications is that the sendfile syscall on my port doesn’t work. To be precise, sendfile sends garbage data to the other side. I have an USB to Ethernet adapter, and using that adapter, the problem disappears. So the conclusion is that my network driver is buggy.

Applications that might be affected are: network servers that sends file (http servers, file servers, etc), distcc.

I will try to fix this tomorrow.

Debian Installation

This is the latest patch (add NAPI to the network driver):

I have uploaded the instruction on how to install Debian on Agestar NCB3AST at:

I am also testing exposing my Agestar NCB3AST to the world, I have installed a web server on my device. The same information above can be accessed at:

Please note that the later URL may not always available. First, my bandwidth is limited, and second, sometimes I still develop and/or test something on it that needs restarting the device.

Debian Etch on Agestar NCB3AST

Powered By DebianFirst the bad news: the network driver in the new kernel is not performing very well, if i remember correctly, this is about twice slower than the original kernel. The maximum speed is around 2.75 mb/s for FTP , 1.4-1.50 mb/s for SAMBA, and 618 kb/s for SSHFS. I have tried implementing NAPI (I will upload the patch soon), but it doesn’t help very much. I have tried to optimize the kernel settings, but no luck so far.

Now, the good news: I have been able to install Debian Etch for ARM in my Agestar using the instruction in here: Of course there are differences in booting, and configuring stuff, but the steps to produce the root file system are the same. I have also managed to write new kernel to the flash (by using dd if=bootpImage of=/dev/mtdblock1), so now my agestar will go directly to Debian when i turned it on.

I will clean up the code, and write the instruction on how to install Debian this weekend.

Latest patch for Agestar NCB3AST


It seems I can get the userland working fine with the latest uClibc snapshot. So far I have been able to boot the kernel using TFTP, and uses root image from NFS and USB, tonight I think I will try to flash the kernel using the mtd driver (for those of you who wants to try before me, flash /dev/mtd1 and use bootpImage for that mtd partition).

Here is the latest patch against (with mtd driver):

Config file for booting with USB root file system. I am using external USB stick (/dev/sdb1) change it to /dev/sdaX to use the hard disk inside Agestar.

Config file for booting NFS root file system. Don’t forget to change the client IP address (mine is, server IP address (mine is and the mount path (mine is /opt/boot).