而第二個的 Sony CXD2837ER 被註冊到 /dev/dvb/adapter0/frontend1 這邊，另外在 LinuxTVWiki 可以看到 CXD2837ER 只被用在了 2018 版本，而且在外觀的部分提到了「or same as 2014 or 2017 revision」，所以看起來手上的版本應該是 2018 版的，但是殼長得跟舊的一樣。
翻了 Sony CXD2837ER 的 datasheet，可以看到支援 DVB-{T2,T,C}：
The Sony CXD2837ER is a combined DVB-T2 (incl.T2-Lite), DVB-T and DVB-C demodulator
Gentoo Linux (pronounced /ˈdʒɛntuː/ JEN-too[3]) is a Linux distribution built using the Portage package management system. Unlike a binary software distribution, the source code is compiled locally according to the user's preferences and is often optimized for the specific type of computer.
For most architectures, this is limited to the core system and weekly updates - not so for amd64 and arm64 however. There we’ve got a stunning >20 GByte of packages on our mirrors, from LibreOffice to KDE Plasma and from Gnome to Docker. Gentoo stable, updated daily.
從文末的圖也可以看到「the amount of binary package data in GByte for each architecture」得資訊：
想得到的客群大概是兩種，第一類是對於想用 Gentoo 看看的人來說會更好入手，尤其是手上是 Raspberry Pi 這些 CPU 不快的 SBC 會方便不少...
Here’s how this works: YouTube URLs look like this: https://www.youtube.com/ watch?v=vXPJVwwEmiM
可以分析出來 vid 包括了 64-bit 的資訊，這個資料型態對工程師來說，看起來就很像是 uniformly distributed：
That bit after “watch?v=” is an 11 digit string. The first ten digits can be a-z,A-Z,0-9 and _-. The last digit is special, and can only be one of 16 values. Turns out there are 2^64 possible YouTube addresses, an enormous number: 18.4 quintillion. There are lots of YouTube videos, but not that many. Let’s guess for a moment that there are 1 billion YouTube videos – if you picked URLs at random, you’d only get a valid address roughly once every 18.4 billion tries.
然後就是隨機去產生 vid 去掃，這個方法跟 drunk dialing 的行為很像，算是 random sampling 的方式：
We refer to this method as “drunk dialing”, as it’s basically as sophisticated as taking swigs from a bottle of bourbon and mashing digits on a telephone, hoping to find a human being to speak to. Jason found a couple of cheats that makes the method roughly 32,000 times as efficient, meaning our “phone call” connects lots more often. Kevin Zheng wrote a whole bunch of scripts to do the dialing, and over the course of several months, we collected more than 10,000 truly random YouTube videos.
另外在 2011 年就有提出來利用 autocomplete 機制去算：
By comparing our results to other ways of generating lists of YouTube videos, we can declare them “plausibly random” if they generate similar results. Fortunately, one method does – it was discovered by Jia Zhou et. al. in 2011, and it’s far more efficient than our naïve method. (You generate a five character string where one character is a dash – YouTube will autocomplete those URLs and spit out a matching video if one exists.) Kevin now polls YouTube using the “dash method” and uses the results to maintain our dashboard at Tubestats.
In our case, our drunk dials tried roughly 32k numbers at the same time, and we got a “hit” every 50,000 times or so. Our current estimate for the size of YouTube is 13.325 billion videos – we are now updating this number every few weeks at tubestats.org.
I planned to spend 1-2 days in the hospital and did not plan to use the laptop.But now I am stuck here for the past two weeks and would like to tinker on small stuff remotely. The hospital has free Wi-fi access.
The caveat is that hospital blocks most connection types. It allows you only to do HTTP (TCP port 80) and HTTPS (TCP port 443) connections for most hosts. DNS (UDP port 53) and DoT (TCP port 853) seem to work as well at least for well-known DNS providers.
But SSH (TCP port 22 or most other custom ports) is blocked completely.
I wondered how hard would it be to pass SSH through HTTP or HTTPS. I had a GSM fallback so I could reconfigure remote server and try various solutions.
