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| In EDK2: How to use the real Libraries (MdePkg) https://forum.osdev.org/viewtopic.php?f=1&t=53936 |
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| Author: | mattibendewald [ Tue Sep 21, 2021 1:12 am ] |
| Post subject: | In EDK2: How to use the real Libraries (MdePkg) |
Hi everyone, I recently started an EDK2 project for a little embedded board. Everything works fine so far, but now I struggle with the serial communication. What I did: I used this Introduction (step by step) to create my application: https://wiki.osdev.org/EDK2 Some additional functionality I added works so far:
Now I wanted to use the serial communication. This is what I tried: In my .dec file: Adding following : Code: [Packages] ... PcAtChipsetPkg/PcAtChipsetPkg.dec UefiCpuPkg/UefiCpuPkg.dec ... [LibraryClasses] ... SerialPortLib|PcAtChipsetPkg/Library/SerialIoLib/SerialIoLib.inf When calling SerialPortInitialize/...Send/...Receive in my main function, it executes those methods from MdePkg/Library/BaseSerialPortLibNull.c instead. (Obviously not sending anything on the serial bus) How can I call the "correct" function instead of that stub/null thing? I tried to search in this forum, also in google for several hours now but can't find the answer yet. Any help would be awesome, thank you for reading!!! |
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| Author: | Ethin [ Wed Sep 22, 2021 2:03 am ] |
| Post subject: | Re: In EDK2: How to use the real Libraries (MdePkg) |
You need to use the EFI Serial IO protocol, not the serial port library. In your [Protocols] section of your .INF file, add: Code: gEfiSerialIoProtocolGuid And then use the Serial IO protocol like you would any other protocol. (For packages/libraries/... you need to create a DXE (for drivers) or application (for EFI applications) with an INF file for each DXE or app, and then include that in a .dsc for your platform. I don't know what the DEC files are for.) |
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| Author: | mattibendewald [ Wed Sep 22, 2021 5:49 am ] |
| Post subject: | Re: In EDK2: How to use the real Libraries (MdePkg) |
Okay, that totally makes sense. Somehow I mixed it up completely, thank you for bringing me back on track! |
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| Author: | Ethin [ Wed Sep 22, 2021 4:17 pm ] |
| Post subject: | Re: In EDK2: How to use the real Libraries (MdePkg) |
mattibendewald wrote: Okay, that totally makes sense. Somehow I mixed it up completely, thank you for bringing me back on track! Understandable; I've made that mistake with TimerLib. EDK II's build system can be confusing, and what libraries to use and avoid can also be confusing. The rule of thumb, I think, is: if a library is a template-based library (that is, if it contains a *Null implementation), use the underlying protocol only; otherwise, you can use the protocol in conjunction with the library. In the (majority) of cases involving purely non-template-based libraries, the libraries extend the functionality of EFI applications that use their associated protocol(s), or provide simpler interfaces to the (possibly more complicated) interfaces provided by the protocol. |
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