Hi Alex,
It's sad that your configuration doesn't work for me.
The vbox config file is test.vbox. I add a node under <ExtraData>:
<ExtraData>
<ExtraDataItem name="GUI/LastGuestSizeHint" value="720,400"/>
<ExtraDataItem name="GUI/LastNormalWindowPosition" value="513,100,720,422"/>
<ExtraDataItem name="CustomVideoMode1" value="1920x1440x16"/>
</ExtraData>
And then I add the kernel parameter vga=864 via boot menu. While testing the resolution was resized back to 1024x768, which is the default value in the original test.vbox:
<VideoCapture enabled="false" screens="18446744073709551615" horzRes="1024" vertRes="768" rate="512" fps="25"/>
And I update the above line to:
<VideoCapture enabled="false" screens="18446744073709551615" horzRes="1920" vertRes="1440" rate="512" fps="25"/>
Still it doesn't work out. The log looks like below[stripped]:
[init -> vbox1] Error: fcntl(): command 2 not supported
[init -> vbox1] Log created: 2017-12-07T15:39:00.000000000Z
[init -> vbox1] main Executable: /virtualbox
[init -> vbox1] Error: SystemPropertiesWrap : Cannot determine default Guest Additions ISO location. Most likely they are not available
[init -> vbox1] i_saveSettings skipped
[init -> fb_drv] Found: VESA BIOS version 3.0
[init -> fb_drv] OEM: Intel(R) Sandybridge/Ivybridge Graphics Chipset Accelerated VGA BIOS
[init -> fb_drv] Found: physical frame buffer at 0xe0000000 size: 67043328
[init -> fb_drv] fb mapped to 0xc000000
[init -> fb_drv] using video mode: 1920x1440@...64...
[init -> vbox1] Using VMX virtualization extension.
[init -> vbox1] Warning: _fpathconf: _fpathconf not implemented
[init -> vbox1] Warning: statfs provides bogus values for '//test.iso' (probably a shared folder)
[init -> vbox1] Warning: fcntl(): command 4 args 4 not supported - terminal
[init -> vbox1] Warning: _sigaction: _sigaction not implemented
[init -> vbox1] Error: fireRuntimeErrorEvent : 0 DrvHostSerialFail Ioctl failed for serial host device '/dev/terminal' (VERR_NOT_SUPPORTED). The device will not work properly
[init -> vbox1] fb resize : [0] 1920x1440 -> 640x480
[init -> vbox1] fb resize : [0] 640x480 -> 720x400
[init -> vbox1] fb resize : [0] 720x400 -> 1920x1440 #1
[init -> vbox1] fb resize : [0] 1920x1440 -> 1024x768
At the very beginning vbox1 found the resolution provided by fb_drv and then resized the screen to 640x480. At #1 it looks like vbox1 found the configuration change and resized the screen to 1920x1440. And finally the screen was resized back to 1024x768.
I would say the resolution 1024x768 is somehow hardcoded into vbox1. Any advice?
Best,
Naiji