i have 2 systems both are exactly the same hardware. on 1st box i installed efi Ubuntu desktop 16.04.4 then upgraded to 4.15.0-43-generic and all works as expected. (i can see my i2c bus\devices )
2nd box was already installed with bios Ubuntu desktop 16.04 kernel 4.4.0-71, Ubuntu dident detected i2c bus\devices correctly. so first step i changed the boot from bios to efi boot loader. system boot ok but still dose not see i2c bus correctly . 2nd step was to upgrade to same kernel as in 1st box 4.15.0-43-generic. after upgrade to 4.15, Ubuntu not loading a lot of drivers for example the i915. Ubuntu also not see the i2c bus at all now (i guess drivers missing )
so why this happen ? same hardware same kernel
how to resolve this ?