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appnote:efidriverdisconnect [2017/07/27 11:52] (current)
nikize created
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 +====== Disconnecting EFI drivers ======
 +This is notes that might help with debugging issues possibly caused by EFI drivers
 +  * Create a disk image with a FAT32 filesystem with [[https://​github.com/​tianocore/​edk2/​raw/​master/​EdkShellBinPkg/​FullShell/​X64/​Shell_Full.efi|UEFI full shell]], saved as ''​\EFI\Boot\BootX64.efi''​
 +  * And something to test the scenario with, //(we will assume ''​ipxe.efi'',​ but change for your scenario)// and save it as ''/​ipxe.efi''​ on the disk
 +  * Boot the troublesome hardware with the just created disk image
 +  * You should get to a UEFI shell prompt. ​ If you then type ''​fs0:''​ and ''​ls''​ you should see your FAT filesystem with ''​ipxe.efi''​
 +  * If not use ''​map''​ to find different ''​fsX:''​ and try them until you find your filesystem.
 +  * Reproduce the issue by running ''​ipxe.efi''​
 +
 +
 +Get in to the shell again
 +  * use ''​drivers -b''​ and ''​devices -b''​ to see a list of handles complete with some kind of textual description
 +//''​-b''​ is used to get one screen of text at a time//
 +  * Find something plausible, try running ''​disconnect <​handle>''​
 +  * where ''<​handle>''​ is the 2- or 3-digit hex value of the handle
 +  * and then retry running ''​ipxe.efi''​ (from the shell, without rebooting first)
 +
 +With Hyper-V as an example we might look for something like: "​Hyper-V",​ "​VMBus",​ "​VmbusDxe",​ "​NetVSC",​ "​RNDIS",​ etc
 +
 +And then looking at ''​devices''​ for where this is connected to, and try to disconnect it from there
 +
 +=== Alternatives to ''​-b''​ on long output ===
 +  * Most efi shell commands supports ''​-b''​ to get paged output
 +  * Most of the time the output is also available on any connected serial port.
 +  * Or pipe output to a file such as ''​drivers > drivers.txt''​ and then use the editor with ''​edit drivers.txt''​ to show it (this requires a writable filesystem)
 +
  
appnote/efidriverdisconnect.txt ยท Last modified: 2017/07/27 11:52 by nikize
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