Showing the residual in petitboot menu when connecting the VGA device

[chcyjoy]

We found VGA or OpenBMC Web KVM will show the residual in petitboot menu when connecting the VGA device. There's no problem in serial console or BMC port 2200.

• Platform: Mihawk

• FW version: Opbuild: v2.3-rc2-409-g6ad3be1 Buildroot: 2019.05.2-11-g8e3337d Skiboot: v6.5.1 Hostboot: a8024a3 Occ: 3472e6c Linux: 5.3.7-openpower1-p1406925 Petitboot: v1.10.4 Machinexml: f6ec5aa Hostbootbinaries: hw080119a.940 Cappucode: p9-dd2-v4 Sbe: 53c1726 Hcode: hw102619a.op940

• Reproduce steps:

  1. Connect a local VGA device to Mihawk machine
  2. Host power on
  3. Boot into Petitboot
  4. Enter system information, system configuration or system status log
  5. Go back to petitboot menu. The residual shows in VGA device or Web KVM Here's the video. residual_in_petiboot.zip

• Current Petitboot patch we used for this issue: https://github.com/alvintpwang/petitboot/commit/cba327862bacf0f133438b3cc7e39d78c8d762b7.patch

[chcyjoy]

@jk-ozlabs Could you please help us check this issue?