Librehat的部落格 – Page 2 – Code can be lovely

Building Linux Kernel on Odroid-U3

This is the year 2020, Odroid-U3 is far from a powerful ARM development board in today’s standard, but it is still more than capable! Quad-core ARMv7 CPU and 2GB RAM, which means I can still run some light services and test my toy projects without paying any fees to AWS or Azure. The year 2020 also means that this little device can be powered by the mainline Linux kernel without many troubles (if any)! Better than that, the process is ridiculously straightforward!

In this post, I put together the steps I did to build the Linux kernel using upstream mainline source code natively on Odroid-U3. If you’re interested in cross-building from your x86 machines, you can find plenty of tutorials on that on the Internet.

Visual Studio Code Server on Android

Microsoft has been steadily enhancing Visual Studio Code Remote Development. One of the components is VS Code Server, which is also open-source and hosted at GitHub. With VS Code Server, you can use Visual Studio Code in a browser. The usual setup involves a server (a VPS perhaps) that hosts the code server. It turns out that it’s also possible to run them locally on your Android device! Here is how.

Announcing YapStocks 2.0

Over the last few weeks, I’ve been working on a new plasmoid (KDE Plasma Applet) that provides a simple interface to monitor stocks. The first version was rather basic, being able to show the current market price only. Now it’s time to announce the availability of the second iteration of YapStocks (Yet Another Plasma Stocks Applet). I’ve recorded a short video clip showcasing all the features it has, ranging from the information summary to the historical price chart.

Hands-on Sailfish OS on Redmi Note 7

Not sure if this is related to the COVID-19 lockdown, but we’ve seen a lot of geeky hobby projects coming up recently. A lot of community ports have been done over the last few months for niche mobile operating systems such as Sailfish OS. That’s exactly the one I played with briefly after purchasing a second-hand Redmi Note 7 on eBay (don’t ask me if I think it’s a waste of money now LOL).

If you come here hoping to find the resources, head to the GitHub repo directly where you can find the ROMs to download.

Make sure that you’ve unlocked the bootloader already! If not, you need to register a MI account and apply for unlocking here. You must log in to your MI account on both the unlocking tool and your phone (MI, POCO, RedMi). If you don’t have a Windows PC, I recommend using XiaoMiTool V2 which works on macOS, Linux, as well as Windows. Though I couldn’t find this on the official FAQ, you have to have a working SIM card inserted. You have to use the mobile data instead of WiFi when unlocking the bootloader on your phone because XiaoMi is doing some verification.

Another problem I encountered was that in fastboot mode, RedMi Note 7 would just say “Press any key to reboot” when any commands are sent from my laptop. After googling on this, there seems to be a driver bug that makes RedMi Note 7 fastboot USB3 unfriendly. Using a USB-Hub worked for most people, including me 🤷.

I wish you all a successful attempt to flash Sailfish OS into your RedMi Note 7. Here are some screenshots I took.

讓你的WordPress小站搭上WebP的快車

Google家開源的WebP圖形編碼格式出來已經好幾年了，瀏覽器支援率現在也是非常高的了（現代瀏覽器就Safari不支持）。相比於常用的JPEG和PNG，使用WebP可以節省高達80%的空間（在今天行動網路的時代，這意味着更快的載入）。

當然了，還是不想拋棄堅守Internet Explorer和蘋果家Safari的用戶，所以我們需要一個聰明的外掛程式，在支援WebP的瀏覽器上使用WebP圖形，不支援的話則提供JPEG或者PNG檔案。隨便Google到的一個頗爲流行的免費開源程式WebP Express就是這輛帶我們上路的快車。

在WordPress後臺Plugins頁面搜尋下載好WebP Express並啓用。如果你使用的是Apache，它開箱即可用。如果你使用的是nginx，則需要按照說明稍微配置一下。這裏用的是nginx，而我選的是簡單的CDN Friendly選項，然後批量將全部圖形檔案轉換成了WebP（原始檔案是不會動的）。Alter HTML那個選項一定要開啓不然什麼也不會發生……

用此前的日本兩京遊記做了一下對比，未啓用掛件的時候頁面大小爲1.8MB，加載用時4.32秒。啓用掛件後頁面大小減少到了1.4MB，加載用時3.52秒。對比提升效果還算明顯，當然了，那篇文章裏面照片很多，一般的文章頁面效果估計甚微。

Use npm packages in QML

I’ve been trying to code up some nice GUI for a hobby project which was done in JavaScript (Node.JS). I’ve looked at a few options that I have

Use the not-yet-stable NodeGUI
Go Web and use Electron
Rewrite the core in Python or C++ to use Qt
Use QML which has limited support for JavaScript

I’ve explored the option 1, however, I soon ran into the problems with the Model/View/Delegate architecture which means I would have to implement native plugins/add-ons in order to use ListView. Not to mention the framework itself is still heavily under development.

As for option 2, I’m not a web frontend engineer and personally I much prefer something that is native (or looks and feels native at least). For the third option, it feels a bit overkill but it is a possible way out.

Luckily I don’t have to do the re-implementation, because I’ve managed to get the core functionality bundled into a single JS file which works flawlessly in the QML environment. Before I start diving into the details on how you can make your npm packages work in QML, I have to emphasise that there are many limitations in the QML environment and it’s very likely that only a small subset of the npm package that you’re interested in is going to work.

OpenSUSE 15.1 Installation Notes

Although my personal laptop isn’t getting much attention from me because I’ve spent most of my time on my work laptop (a MacBook Pro) and my Android tablet (Samsung Galaxy Tab S5e), I’ve decided to take good care of its software over last weekend by wiping the SSD clean and installing a fresh OpenSUSE on it. As an old habit, I’m sharing some notes during the installation and later setup. This is, however, the first blog post written in English here (not counting the old ones on no-long-working en.librehat.com).

WireGuard初體驗

工作和生活很忙的緣故，一直沒有好好維護Shadowsocks的Qt/C++分支，最近下定決心索性聲明好放棄維護了。偶然看到關於WireGuard的新聞，宣稱是一款現代、快速、安全的VPN工具，今天總算抽出來一點時間來試驗一番，下面來分享一下WireGuard之初體驗。

首先，在伺服器和客戶端安裝好WireGuard，官方文檔寫的很詳細。

然後在伺服器和客戶端都創建好一套密鑰文件，命令如下：