Pedaling Upwards

From my previous article Disable pulseaudio in Ubuntu 9.04 I mentioned a weird experience of random hangs (or more precisely, lockups!) when I am using Ubuntu 9.04. This notice is from my office’s Dell’s PC with Intel Quad-core. Nothing special. But it happens randomly. Some lockup includes mouses and keyboard for as long as 1 to 3 minutes, but some lockups are except for mouse and keyboard. I do a lot of googles but to no avail. Seems like I was using the wrong keywords. I came cross this bug report, which was really giving me an insight into this problem, and its possible solution. (even though this bug report was already marked as “invalid”)

So this definitely is not a pulseaudio problem, nor a video driver problem. It may be a kernel problem. The freezes or lockups happened on my two PCs with different sets of hardwares but with same Ubuntu version. It was more like a kernel problem. So I will see if it will disappear after I compiled my own kernel or using a newer version kernel. Well, this is really the weirdest thing I ever had since Ubuntu 5.10. But at this time I have no time to varify the possible solutions described in this bug report (because the lockup is definitely a really annoying experience.. )

I kind of like torturing my computers but end up doing so at myself. I upgraded my AMD PC from Ubuntu 8.10 to 9.10 alpha2 3 weeks ago, and that kept my PC from entering X11 for 1 week until the fglrx driver was fixed. But when it was fixed, I have purchased a Mac mini for my desktop, and returned the AMD PC which was borrowed from my parents. (It was a HTPC in the living room)

Few days ago I issued a command on my notebook in vim at file /etc/apt/sources.list: %s/jaunty/karmic/g, then a sudo apt-get update; sudo apt-get dist-upgrade. Wow.. a dead notebook again...XD The key to solve the booting hangs is listed below. But I think this solution is only valid for this short period of time since it is already listed as bugs on some Ubuntu forums. If you experience booting hangs at:

Begin: Running /scripts/local-bottom ...
Done.
Begin: Running /scripts/init-bottom ...

But how to get to your filesystem if you don’t have CD-rom or BIOS USB-boot function just like my old notebook? Then you should follow some standard procedure of recovering root password, just like this link. The basic procedure is to :

• in GRUB, append init=/bin/bash and boot
• you will end up in a bash shell with your root filesystem mounted as read-only (even if it is listed as rw).
• mount -o remount,rw / OR TRY mount -o remount,rw [/dev/sda1] wherever your root filesystem is.
• If you encounter “bad options” error from mount command, then you should probably fsck your root filesystem before that
  For example, my rootfs is JFS, you should fsck.jfs /dev/sda1 and make sure it is clean before you mount it RW.

最近實在懶得寫騎車日記。累積了兩週，記錄一下最近的三次騎車。這三次剛好都在台北附近，剛好都50km左右或以下的短距離，算是小品。分別是下面三次：

• 9/6：[小格頭]：軍功路->106->深坑、石碇->106乙->北47->小格頭->台9->新店->基隆路 （with味全)
• 9/12:[風櫃嘴]：復興南路->機場地下道->自強隧道->故宮->萬溪產道->風櫃嘴 原路回 (with公司單車社)
• 9/13:[貓空環線]：基隆路->永和->中和南勢角->106->木柵->貓空繞一圈->軍功路->家 (自己騎)

而且現在騎車，幾乎都沒照什麼像，懶得帶相機了說。只有第一次用手機拍了幾張，第二次靠同事分享的照片，第三次則是夜騎，不過台北夜景真的是台灣最漂亮的夜景阿，好讚！不過真的騎公路車，一點都不想帶相機... 下次只能用手機拍拍了...

這是從Kenneth學來的撇步，不知道這個好工具真是太弱了..XD 這個東西基本上就是幫你把C++ manged name給demangle，讓你知道一些link error時的訊息到底出在哪個member functions的工具。直接看examples:

$> c++filt insertValue__7AverageFd
Average::insertValue(double)

$> c++filt _ZN5trend8clooster8antelop37nebular18DataProcessorQueueIPNS_3spn3wrs9AkamaiLogEbE8pushBackEPNS2_13DataProcessorIS7_bEE
trend::clooster::antelop3::nebular::DataProcessorQueue::pushBack(trend::clooster::antelop3::nebular::DataProcessor*)

這不是清楚多了嘛..XD

今天因為project需要，Alex好心的cmake簡易教學，第一次真正接觸CMake，從此只有一個感想：哇靠！我絕對不會想回去寫Makefile或搞什麼autotools了阿！這才叫build automation嘛！於是花了一個下午把Alex給我的example好好研究，大致弄懂cmake怎麼用，然後把我們的project用cmake建立起來，哇，用CMake好爽好輕鬆！最佳入門參考，可以參見jserv學長的[貓也會的CMake]投影片，生動有趣，簡單明瞭。說真的，學長的引言真是讚，不要當個autofool啦，與其花時間在coding，別讓時間都花在寫makefile..XD (<--在說我自己以前)

其中，source tree和binary tree的概念，把source dir和binary dir分開，實在是非常棒的，cmake完全不會用.o/.so/.a和executables來污染source tree。source tree就該只是source tree，多了幾個CMakeLists.txt而已。

Anyway..C stands for Cross-platform，無論是Linux/Unix/Mac/Windows還有Embeded..都非常方便使用..雖然我的世界除了第一者，其他都幾年沒碰過啦。Cmake的介紹不多說，除了jserv的投影片，就是google吧。很容易學的。給個helloworld.c的CMakeLists.txt感覺一下：

PROJECT(helloworld)
SET(hello_SRCS hello.c)
ADD_EXECUTABLE(hello ${hello_SRCS})

而build的方式，就是cd到某空目錄當作binary tree dir，然後cmake [CMakeLists.txt所在目錄]; make即可。

最後，我覺得最爽的就是cmake後make，都會有彩色的字跑出來寫[XX%]Building...XXX... 這也是重點之一，非常清楚好看..XD 比看一對落落長的compiling command舒服太多~ 感謝Alex的教學。