Re: [edk2-discuss] Google Summer of Code Interested Student

["Nate DeSimone" <nathaniel.l.desimone@intel.com>]

Hi Caden,

Great to meet you and welcome to the TianoCore project! Glad you hear you are interested! Sorry it has taken me a while to get back to you, researching the topics you are interested in ended up being somewhat involved 😊.

I went back and did some investigation of current state of the terminal driver, and some of the work has already been done. However, there are some things missing and some odd bugs that need attention. To give you a little more detail, the Terminal driver is located at https://github.com/tianocore/edk2/tree/master/MdeModulePkg/Universal/Console/TerminalDxe

The most prevalent use case for the terminal driver is to display the BIOS setup menu on headless server systems using a PC style serial port connected to a laptop via null modem. This allows administrators to adjust BIOS settings on rack mounted systems without needing to connect a monitor and keyboard.

Historically, the BIOS setup menu would be rendered using the IBM PC VGA text mode, which encoded text using code page 437 (CP437). This was important for box-drawing characters, such as ┌ , ─ , and ┐ , which VGA text mode encodes as 0xDA, 0xC4, and 0xBF respectively. However, most terminal emulators assume text to be encoded in UTF-8. Unicode defines these box drawing characters as 0x250C, 0x2500, and 0x2510. In UTF-8 encoding, these characters translate into 3 byte sequences of (0xE2, 0x94, 0x8C), (0xE2, 0x94, 0x80), and (0xE2, 0x94, 0x90) respectively. The VGA encodings of these box characters will end up generating errors if one attempts to decode them as strict UTF-8, though most terminals assume that the intended characters to be drawn are Ú, Ä, and ¿, which have the Unicode character codes 0xDA, 0xC4, and 0xBF. The end result is the BIOS setup menu looks like this:

ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³                               Device Manager                                 ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ

   Devices List                                          List all the Driver
 > Driver Health Manager                                 Health instances to
 > RAM Disk Configuration                                manage
 > OVMF Platform Configuration
 > iSCSI Configuration
 > Network Device List


   Press ESC to exit.


ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿
³                                                                              ³
³ ^v=Move Highlight       <Enter>=Select Entry      Esc=Exit                   ³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ

Instead of like this:

┌──────────────────────────────────────────────────────────────────────────────┐
│                               Device Manager                                 │
└──────────────────────────────────────────────────────────────────────────────┘

   Devices List                                          List all the Driver
 > Driver Health Manager                                 Health instances to
 > RAM Disk Configuration                                manage
 > OVMF Platform Configuration
 > iSCSI Configuration
 > Network Device List


   Press ESC to exit.


┌──────────────────────────────────────────────────────────────────────────────┐
│                                                                              │
│ ^v=Move Highlight       <Enter>=Select Entry      Esc=Exit                   │
└──────────────────────────────────────────────────────────────────────────────┘

The terminal driver has fully supported both the legacy CP437 encoding and the UTF-8 encoding for more than 10 years now. Which mode to use is part of the configuration settings given to the terminal driver at start up. However, those configuration settings need to come from somewhere. For example, OVMF has the following page in its setup menu for configuring the serial terminal:

┌──────────────────────────────────────────────────────────────────────────────┐
│                             Set COM Attributes                               │
└──────────────────────────────────────────────────────────────────────────────┘

   Set COM Baud Rate          <115200>                   Set COM Baud Rate
   Set COM Data Bits          <8>
   Set COM Parity             <None>
   Set COM Stop Bits          <One>
   Set COM Terminal Type      <PC_ANSI>
   Set COM Flow Control       <None>

   Commit Changes and Exit
   Discard Changes and Exit


┌──────────────────────────────────────────────────────────────────────────────┐
│                         F9=Reset to Defaults      F10=Save                   │
│ ^v=Move Highlight       <Enter>=Select Entry      Esc=Exit                   │
└──────────────────────────────────────────────────────────────────────────────┘

The default terminal type is PC_ANSI, which uses CP437. In this day and age that is probably not the right default anymore, though one could argue whether PC_ANSI being the default is a "bug". Here is the list of supported terminal types:

- PC_ANSI
- VT_100
- VT_100_PLUS
- VT_UTF8 
- TTY_TERM
- LINUX
- XTERM_R6
- VT_400
- SCO

Now, here is the first unquestionable bug. All of these terminal types except for VT_UTF8 output the box drawing characters using CP437. The VT-100 did not use CP437 for box drawing characters. On the VT-100, the terminal driver should output the escape sequence "ESC ( 0" to switch the character set from ASCII to "DEC Special Graphics". Then, while in DEC Special Graphics mode, ┌ , ─ , and ┐ , are encoded as 0x6C, 0x71, and 0x6B respectively. After outputting the box drawing characters, the terminal driver should switch back to ASCII using the escape sequence "ESC ( B". Implementing this will introduce the interesting problem of optimizing display performance by limiting the number of character mode switches.

For all the modes listed above, the VT-100 method should be used for drawing box characters (and other characters in the DEC special graphics character set) with the exception of PC_ANSI and VT_UTF8, which should use CP437 and UTF-8 respectively. In general, DEC special graphics has been around for such a long time that all terminal emulators support it, so it should be the preferred method of outputting characters outside the initial 0-127 basic ASCII codes, with UTF-8 as a fallback if the character can't be encoded by either basic ASCII or DEC special graphics. The difference between VT_UTF8 and the other modes is that DEC special graphics should never be used. PC_ANSI mode should never use DEC special graphics either.

Now, here is the second bug. That BIOS setup menu page that OVMF has for configuring the serial port has a field for setting the terminal type. But, changing the value in that field doesn't actually change the configuration data that is sent to the terminal driver. So the terminal driver always ends up using PC_ANSI mode even if the user changes that setting. This isn’t a bug in the terminal driver really, it’s a bug in OVMF's setup menu implementation. But it does create the appearance of a problem in the terminal driver and should be fixed as part of this GSoC project. This should be fixed in both he OVMF implementation and the MinPlatform implementation.

I'm not sure if the terminal driver improvements would absorb the entire 10 week coding window. If you had time left, you could consider spending it writing unit tests.

Looking at your experience, it seems like you have more experience with Python coding than with C coding. Both the terminal driver improvements and unit tests would be written in C. Another option you could consider is we have a lot of Python code in TianoCore as well. The two major pieces of Python code are BaseTools and EdkRepo. BaseTools provides the build system for TianoCore and implements the logic necessary to compile a BIOS ROM file from source. EdkRepo is the multi-repository tool for EDK II. EdkRepo automates common developer workflows for projects that use more than one git repository (many TianoCore projects do). We would gladly accept project proposals for either BaseTools or EdkRepo. If either of those interest you I can point you to some places where they can be improved and give you some project ideas.

The most important outcome from GSoC in our view is that our students learn something, get some exposure, and have a great experience that they will remember fondly for years to come. We want you to be successful. Gauge your comfort level and pick a project that you feel you can achieve in the 10 week period. Sorry for the long email, but I hope it helps. Finally I'd like to reiterate... Welcome to the project!

With Best Regards,
Nate

-----Original Message-----
From: Laszlo Ersek <lersek@redhat.com> 
Sent: Wednesday, March 10, 2021 8:17 AM
To: discuss@edk2.groups.io
Cc: cadenkline9@gmail.com; Desimone, Nathaniel L <nathaniel.l.desimone@intel.com>
Subject: Re: [edk2-discuss] Google Summer of Code Interested Student

adding Nate

On 03/10/21 03:10, mailto:cadenkline9@gmail.com wrote:
> Hello, My name is Caden Kline. I am a freshmen Computer Science major in the US. I intend to specialize in Systems or Security or both. The main two tasks I am hoping to apply for are "Terminal driver improvements" and "Writing Unit Tests".  However, I am primarily interested in any system level work and willing to work on anything. I am concerned about the difficulty in completing these tasks so I'm going to list my experience.   
> 
> My relevant experience for C programming language is a one semester introduction to C and Unix class I am currently taking. Outside of formal experience, I have primarily interacted with C and assembly with capture the flag/wargame binary exploitation challenges, and unfinished projects such as a chip8 emulator. My primary programming experience is Java and Python thanks to my high school and college classes. I have participated in several past google code-ins.  My github profile is https://github.com/Pokemod97 . 
> 
> Is there anything I can do to improve my chances to be selected or any other feedback? Thank you for taking the time to read this message.
> 
> 
> 
> 
>