Int10h handler comes with a macro, when enabled before compiling, that will enable serial console output which can be used to debug the handler itself.
UefiSeven also contains a hack to enable screen output on hardwares that do not natively support 1024x768 as is needed by Windows Installer. UefiSeven installs a minimal Int10h handler in the memory before Windows boots up so that the boot process do not fail because of the missing interrupt. Some motherboards have 'CSM' or 'legacy' boot options to fix this problem but it is getting increasingly rare as Intel decided to get rid of legacy BIOS support by 2020, and the option is virtually non-existent on consumer mobile devices. On computers without proper legacy support Windows 7 might freeze on 'Starting Windows' screen or fail with error code 0xc000000d. Windows 7 does not fully support UEFI and relies on legacy BIOS interrupt 10 (Int10h) during initial graphics initialization. UefiSeven is an efi module that enables Windows 7 to boot under UEFI Class 3 systems.
