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Gotchas for me

Here are some of the gotchas I came across. They might look stupid. But I hope they could be useful for somebody.

  • When you work on a big endian system, first make sure your compiler actually support big-endian and you have the correct big-endian libraries.
  • It'll really save you a lot of time to just install a linux system and work on that platform other than spending lots of efforts to make the tool chains and uclinux source tree compiles under CYGWIN.
  • If you do want to use CYGWIN, here are some more advices.
      1. You can download the tar ball from the tool chain link on my web site. It was precompiled with everything in place for little and big endian.
      2. Make sure you work on a WindowsNT/2000/XP system and make sure your CYGWIN installation is on a NTFS partition. This is very important because the romfs installation script will try to make hard links while the FAT32 partition doesn't support.
      3. Make sure you install the TCL/TK package of CYGWIN if you want to use "make xconfig"
  • There are some problems with big endian system for calculating TCP checksums. The fixes has already been submitted to the uclinux CVS but somehow I got a earlier version. If you want to know more about it, just google "uclinux tcp checksum" and you will get it.
  • Oh, man! You gotta enable your cache in the CPU. The S3C4510 runs like a turtle with the cache turned off. It only showed up as 8MIPS comparing to 50MIPS with the cache on.
  • With the cache on, remember to access your externa I/O device using the non-cachable memory maping because obviously that is not a real SDRAM. The external RTL8019 ethernet controller with stop working if you use the cachable address with the cache on.
  • If you use sash, the piping on the command line doesn't seem to be working. So for the ip_forwarding enable you have to create a file with a "1" in it like /etc/1 and use "cp /etc/1 /proc/sys/net/ipv4/ip_forward" to do the trick.

© 2005 Zibo Zhao | Last update: 2/23/2005