QEMU VC (graphical terminal) fixes

[rouming]

Hey folks,

With this PR I brought a several upstream QEMU fixes, which target QEMU terminal (console-vc) bugs, making graphical console (e.g. VNC) more usable and aligning it better with VT100 spec. The updates include support for inserting and deleting characters, better cursor handling and correct position reporting.

The most annoying issue you can observe in the EVE VNC shim console, when the shell prompt always contains terminal escape symbols at the end, something like this:

      ~# ^[[20;1R

This is fixed by the following backported patch:
27-qemu--ui-console-vc-report-to-the-application-instead-of-s.patch

Summary of included patches:

1. Handle ESC ( <ch> character set sequences

   • Makes top output look clean by handling the character set
     commands.

2. Ensure DSR (Device Status Report) responses go to applications

   • Stops terminal from rendering responses to the screen but instead
     send reports back to applications.

3. Fix cursor position reporting

   • Reports cursor position relative to the screen instead of the
     scroll buffer.
   • Fixes issues with tools that rely on accurate cursor placement.

4. Support for DCH (delete) and ICH (insert) commands

   • Properly handles character deletion and insertion as per VT100
     specs.

This was tested using eden, the following docker image docker://lfedge/eden-eclient:b1c1de6 and latest EVE master.

Rise and shine, shim VM console. Rise and shine!

[rene]

Thanks @rouming , LGTM

[naiming-zededa]

Hey @rouming thanks. I'm also thinking we have this 'kubevirt' which uses k3s/kubevirt to launch the VM on EVE device, they call it VMI, the code for create vmi (a replicaSet config). we can use 'kubectl [vnc | console] ' to access the VMI VNC/console, but in the shim-VM for container inside, i'm not sure if there is way to pass in some 'console' or 'serial' type of config in their kubevirt API or yaml to replicate the similar thing for the 'shim-console' kind of mapping. Any idea? thanks.

[rouming]

Hi @naiming-zededa, I'm not an expert in kubevirt at all, but if this layer starts QEMU based VM, then it should not be a problem to have a similar thing by passing the correct config to the QEMU, but unfortunately I have no idea how this thing (kubevirt) works and what API does it support, sorry about that.