video_terminal : blank appearing on exported screen when using hdmi connecting

[allrighteveryday]

hi,

when running linux(linux-on-litex-vexriscv) on my board, there is some difference between the terminal on my computer and the exported screen(connected to the board with hdmi) . it seems some characters missing (eg.Large blank space appearing as shown in the figure)

how can i fix it ?
any help appreciated :)