`g_FATFS_Obj` is located in `__DMA` section, which is not initialised, so that testing `sdMounted()` at boot relies on the fact that the bootloader linker script declares BSS in internal SRAM and not in CCM, as the firmware linker script does.
`g_FATFS_Obj` is located in `__DMA` section, which is not initialised, so that testing `sdMounted()` at boot relies on the fact that the bootloader linker script declares BSS in internal SRAM and not in CCM, as the firmware linker script does.