Question on initrd and initramfs

[Ezequiel Garcia]

On Fri, Sep 28, 2012 at 7:53 AM, Ezequiel Garcia <elezegarcia at gmail.com> wrote:
> On Thu, Sep 27, 2012 at 2:43 PM, Autif Khan <autif.mlist at gmail.com> wrote:
>> On Thu, Sep 27, 2012 at 12:57 PM, Ezequiel Garcia <elezegarcia at gmail.com> wrote:
>>>
>>> Now to my first question:
>>> The kernel is compiled WITHOUT any fs driver... So how the f@#ck did
>>> he mounted initramfs? How are the files formatted?
>>
>> It would help if you post the kernel config in its entirety
>
> #
> # Automatically generated file; DO NOT EDIT.
> # Linux/i386 3.6.0-rc1 Kernel Configuration
> #
> # CONFIG_64BIT is not set
> CONFIG_X86_32=y
> # CONFIG_X86_64 is not set
> CONFIG_X86=y
> CONFIG_INSTRUCTION_DECODER=y
> CONFIG_OUTPUT_FORMAT="elf32-i386"
> CONFIG_ARCH_DEFCONFIG="arch/x86/configs/i386_defconfig"
> CONFIG_LOCKDEP_SUPPORT=y
> CONFIG_STACKTRACE_SUPPORT=y
> CONFIG_HAVE_LATENCYTOP_SUPPORT=y
> CONFIG_MMU=y
> # CONFIG_NEED_DMA_MAP_STATE is not set
> CONFIG_NEED_SG_DMA_LENGTH=y
> CONFIG_GENERIC_ISA_DMA=y
> CONFIG_GENERIC_HWEIGHT=y
> CONFIG_ARCH_MAY_HAVE_PC_FDC=y
> # CONFIG_RWSEM_GENERIC_SPINLOCK is not set
> CONFIG_RWSEM_XCHGADD_ALGORITHM=y
> CONFIG_GENERIC_CALIBRATE_DELAY=y
> CONFIG_ARCH_HAS_CPU_RELAX=y
> CONFIG_ARCH_HAS_DEFAULT_IDLE=y
> CONFIG_ARCH_HAS_CACHE_LINE_SIZE=y
> CONFIG_ARCH_HAS_CPU_AUTOPROBE=y
> CONFIG_HAVE_SETUP_PER_CPU_AREA=y
> CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK=y
> CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK=y
> CONFIG_ARCH_HIBERNATION_POSSIBLE=y
> CONFIG_ARCH_SUSPEND_POSSIBLE=y
> # CONFIG_ZONE_DMA32 is not set
> # CONFIG_AUDIT_ARCH is not set
> CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING=y
> CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC=y
> CONFIG_X86_32_LAZY_GS=y
> CONFIG_ARCH_HWEIGHT_CFLAGS="-fcall-saved-ecx -fcall-saved-edx"
> CONFIG_ARCH_SUPPORTS_UPROBES=y
> CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config"
> CONFIG_HAVE_IRQ_WORK=y
> CONFIG_IRQ_WORK=y
> CONFIG_BUILDTIME_EXTABLE_SORT=y
>
> #
> # General setup
> #
> # CONFIG_EXPERIMENTAL is not set
> CONFIG_BROKEN_ON_SMP=y
> CONFIG_INIT_ENV_ARG_LIMIT=32
> CONFIG_CROSS_COMPILE=""
> CONFIG_LOCALVERSION="-linuxtv"
> # CONFIG_LOCALVERSION_AUTO is not set
> CONFIG_HAVE_KERNEL_GZIP=y
> CONFIG_HAVE_KERNEL_BZIP2=y
> CONFIG_HAVE_KERNEL_LZMA=y
> CONFIG_HAVE_KERNEL_XZ=y
> CONFIG_HAVE_KERNEL_LZO=y
> CONFIG_KERNEL_GZIP=y
> # CONFIG_KERNEL_BZIP2 is not set
> # CONFIG_KERNEL_LZMA is not set
> # CONFIG_KERNEL_XZ is not set
> # CONFIG_KERNEL_LZO is not set
> CONFIG_DEFAULT_HOSTNAME="(none)"
> # CONFIG_SWAP is not set
> # CONFIG_SYSVIPC is not set
> # CONFIG_BSD_PROCESS_ACCT is not set
> # CONFIG_FHANDLE is not set
> CONFIG_HAVE_GENERIC_HARDIRQS=y
>
> #
> # IRQ subsystem
> #
> CONFIG_GENERIC_HARDIRQS=y
> CONFIG_GENERIC_IRQ_PROBE=y
> CONFIG_GENERIC_IRQ_SHOW=y
> CONFIG_IRQ_FORCED_THREADING=y
> CONFIG_SPARSE_IRQ=y
> CONFIG_CLOCKSOURCE_WATCHDOG=y
> CONFIG_KTIME_SCALAR=y
> CONFIG_GENERIC_CLOCKEVENTS=y
> CONFIG_GENERIC_CLOCKEVENTS_BUILD=y
> CONFIG_GENERIC_CLOCKEVENTS_MIN_ADJUST=y
> CONFIG_GENERIC_CMOS_UPDATE=y
>
> #
> # Timers subsystem
> #
> CONFIG_TICK_ONESHOT=y
> CONFIG_NO_HZ=y
> CONFIG_HIGH_RES_TIMERS=y
>
> #
> # RCU Subsystem
> #
> CONFIG_TINY_RCU=y
> # CONFIG_PREEMPT_RCU is not set
> # CONFIG_TREE_RCU_TRACE is not set
> # CONFIG_IKCONFIG is not set
> CONFIG_LOG_BUF_SHIFT=21
> CONFIG_HAVE_UNSTABLE_SCHED_CLOCK=y
> # CONFIG_CHECKPOINT_RESTORE is not set
> # CONFIG_NAMESPACES is not set
> # CONFIG_SCHED_AUTOGROUP is not set
> # CONFIG_RELAY is not set
> CONFIG_BLK_DEV_INITRD=y
> CONFIG_INITRAMFS_SOURCE=""
> # CONFIG_RD_GZIP is not set
> # CONFIG_RD_BZIP2 is not set
> # CONFIG_RD_LZMA is not set
> # CONFIG_RD_XZ is not set
> # CONFIG_RD_LZO is not set
> CONFIG_CC_OPTIMIZE_FOR_SIZE=y
> CONFIG_ANON_INODES=y
> CONFIG_EXPERT=y
> # CONFIG_UID16 is not set
> # CONFIG_KALLSYMS is not set
> CONFIG_HOTPLUG=y
> # CONFIG_PRINTK is not set
> # CONFIG_BUG is not set
> # CONFIG_ELF_CORE is not set
> # CONFIG_PCSPKR_PLATFORM is not set
> CONFIG_HAVE_PCSPKR_PLATFORM=y
> # CONFIG_BASE_FULL is not set
> # CONFIG_FUTEX is not set
> # CONFIG_EPOLL is not set
> # CONFIG_SIGNALFD is not set
> # CONFIG_TIMERFD is not set
> # CONFIG_EVENTFD is not set
> # CONFIG_SHMEM is not set
> # CONFIG_AIO is not set
> CONFIG_EMBEDDED=y
> CONFIG_HAVE_PERF_EVENTS=y
>
> #
> # Kernel Performance Events And Counters
> #
> CONFIG_PERF_EVENTS=y
> # CONFIG_DEBUG_PERF_USE_VMALLOC is not set
> # CONFIG_VM_EVENT_COUNTERS is not set
> # CONFIG_COMPAT_BRK is not set
> # CONFIG_SLAB is not set
> # CONFIG_SLUB is not set
> CONFIG_SLOB=y
> # CONFIG_PROFILING is not set
> CONFIG_HAVE_OPROFILE=y
> CONFIG_OPROFILE_NMI_TIMER=y
> # CONFIG_JUMP_LABEL is not set
> CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y
> CONFIG_HAVE_IOREMAP_PROT=y
> CONFIG_HAVE_KPROBES=y
> CONFIG_HAVE_KRETPROBES=y
> CONFIG_HAVE_OPTPROBES=y
> CONFIG_HAVE_ARCH_TRACEHOOK=y
> CONFIG_HAVE_DMA_ATTRS=y
> CONFIG_HAVE_DMA_CONTIGUOUS=y
> CONFIG_GENERIC_SMP_IDLE_THREAD=y
> CONFIG_HAVE_REGS_AND_STACK_ACCESS_API=y
> CONFIG_HAVE_DMA_API_DEBUG=y
> CONFIG_HAVE_HW_BREAKPOINT=y
> CONFIG_HAVE_MIXED_BREAKPOINTS_REGS=y
> CONFIG_HAVE_USER_RETURN_NOTIFIER=y
> CONFIG_HAVE_PERF_EVENTS_NMI=y
> CONFIG_HAVE_ARCH_JUMP_LABEL=y
> CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG=y
> CONFIG_HAVE_CMPXCHG_LOCAL=y
> CONFIG_HAVE_CMPXCHG_DOUBLE=y
> CONFIG_ARCH_WANT_IPC_PARSE_VERSION=y
> CONFIG_HAVE_ARCH_SECCOMP_FILTER=y
>
> #
> # GCOV-based kernel profiling
> #
> CONFIG_HAVE_GENERIC_DMA_COHERENT=y
> CONFIG_BASE_SMALL=1
> # CONFIG_MODULES is not set
> CONFIG_BLOCK=y
> # CONFIG_LBDAF is not set
> # CONFIG_BLK_DEV_BSG is not set
> # CONFIG_BLK_DEV_BSGLIB is not set
> # CONFIG_BLK_DEV_INTEGRITY is not set
>
> #
> # Partition Types
> #
> # CONFIG_PARTITION_ADVANCED is not set
> CONFIG_MSDOS_PARTITION=y
>
> #
> # IO Schedulers
> #
> CONFIG_IOSCHED_NOOP=y
> # CONFIG_IOSCHED_DEADLINE is not set
> # CONFIG_IOSCHED_CFQ is not set
> CONFIG_DEFAULT_NOOP=y
> CONFIG_DEFAULT_IOSCHED="noop"
> # CONFIG_INLINE_SPIN_TRYLOCK is not set
> # CONFIG_INLINE_SPIN_TRYLOCK_BH is not set
> # CONFIG_INLINE_SPIN_LOCK is not set
> # CONFIG_INLINE_SPIN_LOCK_BH is not set
> # CONFIG_INLINE_SPIN_LOCK_IRQ is not set
> # CONFIG_INLINE_SPIN_LOCK_IRQSAVE is not set
> # CONFIG_INLINE_SPIN_UNLOCK_BH is not set
> CONFIG_INLINE_SPIN_UNLOCK_IRQ=y
> # CONFIG_INLINE_SPIN_UNLOCK_IRQRESTORE is not set
> # CONFIG_INLINE_READ_TRYLOCK is not set
> # CONFIG_INLINE_READ_LOCK is not set
> # CONFIG_INLINE_READ_LOCK_BH is not set
> # CONFIG_INLINE_READ_LOCK_IRQ is not set
> # CONFIG_INLINE_READ_LOCK_IRQSAVE is not set
> CONFIG_INLINE_READ_UNLOCK=y
> # CONFIG_INLINE_READ_UNLOCK_BH is not set
> CONFIG_INLINE_READ_UNLOCK_IRQ=y
> # CONFIG_INLINE_READ_UNLOCK_IRQRESTORE is not set
> # CONFIG_INLINE_WRITE_TRYLOCK is not set
> # CONFIG_INLINE_WRITE_LOCK is not set
> # CONFIG_INLINE_WRITE_LOCK_BH is not set
> # CONFIG_INLINE_WRITE_LOCK_IRQ is not set
> # CONFIG_INLINE_WRITE_LOCK_IRQSAVE is not set
> CONFIG_INLINE_WRITE_UNLOCK=y
> # CONFIG_INLINE_WRITE_UNLOCK_BH is not set
> CONFIG_INLINE_WRITE_UNLOCK_IRQ=y
> # CONFIG_INLINE_WRITE_UNLOCK_IRQRESTORE is not set
> # CONFIG_MUTEX_SPIN_ON_OWNER is not set
> # CONFIG_FREEZER is not set
>
> #
> # Processor type and features
> #
> # CONFIG_ZONE_DMA is not set
> # CONFIG_SMP is not set
> # CONFIG_X86_EXTENDED_PLATFORM is not set
> # CONFIG_X86_32_IRIS is not set
> # CONFIG_SCHED_OMIT_FRAME_POINTER is not set
> # CONFIG_PARAVIRT_GUEST is not set
> CONFIG_NO_BOOTMEM=y
> # CONFIG_MEMTEST is not set
> # CONFIG_M386 is not set
> # CONFIG_M486 is not set
> # CONFIG_M586 is not set
> # CONFIG_M586TSC is not set
> # CONFIG_M586MMX is not set
> CONFIG_M686=y
> # CONFIG_MPENTIUMII is not set
> # CONFIG_MPENTIUMIII is not set
> # CONFIG_MPENTIUMM is not set
> # CONFIG_MPENTIUM4 is not set
> # CONFIG_MK6 is not set
> # CONFIG_MK7 is not set
> # CONFIG_MK8 is not set
> # CONFIG_MCRUSOE is not set
> # CONFIG_MEFFICEON is not set
> # CONFIG_MWINCHIPC6 is not set
> # CONFIG_MWINCHIP3D is not set
> # CONFIG_MELAN is not set
> # CONFIG_MGEODEGX1 is not set
> # CONFIG_MGEODE_LX is not set
> # CONFIG_MCYRIXIII is not set
> # CONFIG_MVIAC3_2 is not set
> # CONFIG_MVIAC7 is not set
> # CONFIG_MCORE2 is not set
> # CONFIG_MATOM is not set
> CONFIG_X86_GENERIC=y
> CONFIG_X86_INTERNODE_CACHE_SHIFT=6
> CONFIG_X86_CMPXCHG=y
> CONFIG_X86_L1_CACHE_SHIFT=6
> CONFIG_X86_XADD=y
> # CONFIG_X86_PPRO_FENCE is not set
> CONFIG_X86_WP_WORKS_OK=y
> CONFIG_X86_INVLPG=y
> CONFIG_X86_BSWAP=y
> CONFIG_X86_POPAD_OK=y
> CONFIG_X86_INTEL_USERCOPY=y
> CONFIG_X86_USE_PPRO_CHECKSUM=y
> CONFIG_X86_TSC=y
> CONFIG_X86_CMPXCHG64=y
> CONFIG_X86_CMOV=y
> CONFIG_X86_MINIMUM_CPU_FAMILY=5
> CONFIG_X86_DEBUGCTLMSR=y
> # CONFIG_PROCESSOR_SELECT is not set
> CONFIG_CPU_SUP_INTEL=y
> CONFIG_CPU_SUP_CYRIX_32=y
> CONFIG_CPU_SUP_AMD=y
> CONFIG_CPU_SUP_CENTAUR=y
> CONFIG_CPU_SUP_TRANSMETA_32=y
> CONFIG_CPU_SUP_UMC_32=y
> # CONFIG_HPET_TIMER is not set
> # CONFIG_DMI is not set
> # CONFIG_IOMMU_HELPER is not set
> CONFIG_NR_CPUS=1
> # CONFIG_IRQ_TIME_ACCOUNTING is not set
> CONFIG_PREEMPT_NONE=y
> # CONFIG_PREEMPT_VOLUNTARY is not set
> # CONFIG_PREEMPT is not set
> # CONFIG_X86_UP_APIC is not set
> # CONFIG_X86_MCE is not set
> # CONFIG_VM86 is not set
> # CONFIG_TOSHIBA is not set
> # CONFIG_I8K is not set
> # CONFIG_X86_REBOOTFIXUPS is not set
> # CONFIG_MICROCODE is not set
> # CONFIG_X86_MSR is not set
> # CONFIG_X86_CPUID is not set
> CONFIG_NOHIGHMEM=y
> # CONFIG_HIGHMEM4G is not set
> # CONFIG_HIGHMEM64G is not set
> CONFIG_PAGE_OFFSET=0xC0000000
> # CONFIG_X86_PAE is not set
> # CONFIG_ARCH_PHYS_ADDR_T_64BIT is not set
> # CONFIG_ARCH_DMA_ADDR_T_64BIT is not set
> CONFIG_ARCH_FLATMEM_ENABLE=y
> CONFIG_ILLEGAL_POINTER_VALUE=0
> CONFIG_FLATMEM=y
> CONFIG_FLAT_NODE_MEM_MAP=y
> CONFIG_HAVE_MEMBLOCK=y
> CONFIG_HAVE_MEMBLOCK_NODE_MAP=y
> CONFIG_ARCH_DISCARD_MEMBLOCK=y
> CONFIG_PAGEFLAGS_EXTENDED=y
> CONFIG_SPLIT_PTLOCK_CPUS=4
> # CONFIG_COMPACTION is not set
> # CONFIG_PHYS_ADDR_T_64BIT is not set
> CONFIG_ZONE_DMA_FLAG=0
> CONFIG_VIRT_TO_BUS=y
> # CONFIG_KSM is not set
> CONFIG_DEFAULT_MMAP_MIN_ADDR=4096
> # CONFIG_TRANSPARENT_HUGEPAGE is not set
> # CONFIG_CROSS_MEMORY_ATTACH is not set
> CONFIG_NEED_PER_CPU_KM=y
> # CONFIG_CLEANCACHE is not set
> # CONFIG_X86_CHECK_BIOS_CORRUPTION is not set
> CONFIG_X86_RESERVE_LOW=64
> # CONFIG_MATH_EMULATION is not set
> # CONFIG_MTRR is not set
> # CONFIG_ARCH_RANDOM is not set
> # CONFIG_SECCOMP is not set
> # CONFIG_CC_STACKPROTECTOR is not set
> CONFIG_HZ_100=y
> # CONFIG_HZ_250 is not set
> # CONFIG_HZ_300 is not set
> # CONFIG_HZ_1000 is not set
> CONFIG_HZ=100
> CONFIG_SCHED_HRTICK=y
> # CONFIG_KEXEC is not set
> CONFIG_PHYSICAL_START=0x1000000
> CONFIG_RELOCATABLE=y
> CONFIG_X86_NEED_RELOCS=y
> CONFIG_PHYSICAL_ALIGN=0x1000000
> # CONFIG_COMPAT_VDSO is not set
> # CONFIG_CMDLINE_BOOL is not set
>
> #
> # Power management and ACPI options
> #
> # CONFIG_SUSPEND is not set
> # CONFIG_PM_RUNTIME is not set
> # CONFIG_SFI is not set
>
> #
> # CPU Frequency scaling
> #
> # CONFIG_CPU_FREQ is not set
> # CONFIG_CPU_IDLE is not set
> # CONFIG_ARCH_NEEDS_CPU_IDLE_COUPLED is not set
>
> #
> # Bus options (PCI etc.)
> #
> # CONFIG_PCI is not set
> # CONFIG_ARCH_SUPPORTS_MSI is not set
> CONFIG_ISA_DMA_API=y
> # CONFIG_ISA is not set
> # CONFIG_SCx200 is not set
> # CONFIG_OLPC is not set
> # CONFIG_ALIX is not set
> # CONFIG_NET5501 is not set
> # CONFIG_PCCARD is not set
>
> #
> # Executable file formats / Emulations
> #
> CONFIG_BINFMT_ELF=y
> CONFIG_ARCH_BINFMT_ELF_RANDOMIZE_PIE=y
> CONFIG_HAVE_AOUT=y
> # CONFIG_BINFMT_AOUT is not set
> CONFIG_BINFMT_MISC=y
> CONFIG_HAVE_ATOMIC_IOMAP=y
> CONFIG_HAVE_TEXT_POKE_SMP=y
> # CONFIG_NET is not set
>
> #
> # Device Drivers
> #
>
> #
> # Generic Driver Options
> #
> CONFIG_UEVENT_HELPER_PATH=""
> CONFIG_DEVTMPFS=y
> CONFIG_DEVTMPFS_MOUNT=y
> CONFIG_STANDALONE=y
> # CONFIG_PREVENT_FIRMWARE_BUILD is not set
> # CONFIG_FW_LOADER is not set
> # CONFIG_DEBUG_DRIVER is not set
> # CONFIG_DEBUG_DEVRES is not set
> # CONFIG_SYS_HYPERVISOR is not set
> # CONFIG_GENERIC_CPU_DEVICES is not set
> # CONFIG_MTD is not set
> # CONFIG_PARPORT is not set
> # CONFIG_BLK_DEV is not set
>
> #
> # Misc devices
> #
> # CONFIG_SENSORS_LIS3LV02D is not set
> # CONFIG_ENCLOSURE_SERVICES is not set
> # CONFIG_VMWARE_BALLOON is not set
>
> #
> # EEPROM support
> #
> # CONFIG_EEPROM_93CX6 is not set
>
> #
> # Texas Instruments shared transport line discipline
> #
>
> #
> # Altera FPGA firmware download module
> #
> CONFIG_HAVE_IDE=y
> # CONFIG_IDE is not set
>
> #
> # SCSI device support
> #
> CONFIG_SCSI_MOD=y
> # CONFIG_RAID_ATTRS is not set
> # CONFIG_SCSI is not set
> # CONFIG_SCSI_DMA is not set
> # CONFIG_SCSI_NETLINK is not set
> # CONFIG_ATA is not set
> # CONFIG_MD is not set
> # CONFIG_MACINTOSH_DRIVERS is not set
>
> #
> # Input device support
> #
> CONFIG_INPUT=y
> # CONFIG_INPUT_FF_MEMLESS is not set
> # CONFIG_INPUT_POLLDEV is not set
> # CONFIG_INPUT_SPARSEKMAP is not set
> # CONFIG_INPUT_MATRIXKMAP is not set
>
> #
> # Userland interfaces
> #
> CONFIG_INPUT_MOUSEDEV=y
> CONFIG_INPUT_MOUSEDEV_PSAUX=y
> CONFIG_INPUT_MOUSEDEV_SCREEN_X=1024
> CONFIG_INPUT_MOUSEDEV_SCREEN_Y=768
> # CONFIG_INPUT_JOYDEV is not set
> # CONFIG_INPUT_EVDEV is not set
> # CONFIG_INPUT_EVBUG is not set
>
> #
> # Input Device Drivers
> #
> CONFIG_INPUT_KEYBOARD=y
> CONFIG_KEYBOARD_ATKBD=y
> # CONFIG_KEYBOARD_LKKBD is not set
> # CONFIG_KEYBOARD_NEWTON is not set
> # CONFIG_KEYBOARD_OPENCORES is not set
> # CONFIG_KEYBOARD_STOWAWAY is not set
> # CONFIG_KEYBOARD_SUNKBD is not set
> # CONFIG_KEYBOARD_OMAP4 is not set
> # CONFIG_KEYBOARD_XTKBD is not set
> CONFIG_INPUT_MOUSE=y
> CONFIG_MOUSE_PS2=y
> CONFIG_MOUSE_PS2_ALPS=y
> CONFIG_MOUSE_PS2_LOGIPS2PP=y
> CONFIG_MOUSE_PS2_SYNAPTICS=y
> CONFIG_MOUSE_PS2_TRACKPOINT=y
> # CONFIG_MOUSE_PS2_ELANTECH is not set
> # CONFIG_MOUSE_PS2_SENTELIC is not set
> # CONFIG_MOUSE_PS2_TOUCHKIT is not set
> # CONFIG_MOUSE_SERIAL is not set
> # CONFIG_MOUSE_VSXXXAA is not set
> # CONFIG_INPUT_JOYSTICK is not set
> # CONFIG_INPUT_TABLET is not set
> # CONFIG_INPUT_TOUCHSCREEN is not set
> # CONFIG_INPUT_MISC is not set
>
> #
> # Hardware I/O ports
> #
> CONFIG_SERIO=y
> CONFIG_SERIO_I8042=y
> CONFIG_SERIO_SERPORT=y
> # CONFIG_SERIO_CT82C710 is not set
> CONFIG_SERIO_LIBPS2=y
> # CONFIG_SERIO_RAW is not set
> # CONFIG_SERIO_ALTERA_PS2 is not set
> # CONFIG_SERIO_PS2MULT is not set
> # CONFIG_GAMEPORT is not set
>
> #
> # Character devices
> #
> CONFIG_VT=y
> # CONFIG_CONSOLE_TRANSLATIONS is not set
> CONFIG_VT_CONSOLE=y
> CONFIG_HW_CONSOLE=y
> # CONFIG_VT_HW_CONSOLE_BINDING is not set
> # CONFIG_UNIX98_PTYS is not set
> # CONFIG_LEGACY_PTYS is not set
> # CONFIG_SERIAL_NONSTANDARD is not set
> # CONFIG_TRACE_SINK is not set
> # CONFIG_DEVKMEM is not set
>
> #
> # Serial drivers
> #
> # CONFIG_SERIAL_8250 is not set
> CONFIG_FIX_EARLYCON_MEM=y
>
> #
> # Non-8250 serial port support
> #
> # CONFIG_SERIAL_TIMBERDALE is not set
> # CONFIG_SERIAL_ALTERA_JTAGUART is not set
> # CONFIG_SERIAL_ALTERA_UART is not set
> # CONFIG_SERIAL_XILINX_PS_UART is not set
> # CONFIG_TTY_PRINTK is not set
> # CONFIG_IPMI_HANDLER is not set
> # CONFIG_HW_RANDOM is not set
> # CONFIG_NVRAM is not set
> # CONFIG_RTC is not set
> # CONFIG_GEN_RTC is not set
> # CONFIG_R3964 is not set
> # CONFIG_MWAVE is not set
> # CONFIG_PC8736x_GPIO is not set
> # CONFIG_NSC_GPIO is not set
> # CONFIG_RAW_DRIVER is not set
> # CONFIG_HANGCHECK_TIMER is not set
> # CONFIG_TCG_TPM is not set
> # CONFIG_I2C is not set
> # CONFIG_SPI is not set
> # CONFIG_HSI is not set
>
> #
> # PPS support
> #
>
> #
> # PPS generators support
> #
>
> #
> # PTP clock support
> #
>
> #
> # Enable Device Drivers -> PPS to see the PTP clock options.
> #
> CONFIG_ARCH_WANT_OPTIONAL_GPIOLIB=y
> # CONFIG_GPIOLIB is not set
> # CONFIG_W1 is not set
> # CONFIG_POWER_SUPPLY is not set
> # CONFIG_POWER_AVS is not set
> # CONFIG_HWMON is not set
> # CONFIG_THERMAL is not set
> # CONFIG_WATCHDOG is not set
> CONFIG_SSB_POSSIBLE=y
>
> #
> # Sonics Silicon Backplane
> #
> # CONFIG_SSB is not set
> CONFIG_BCMA_POSSIBLE=y
>
> #
> # Broadcom specific AMBA
> #
> # CONFIG_BCMA is not set
>
> #
> # Multifunction device drivers
> #
> # CONFIG_MFD_CORE is not set
> # CONFIG_MFD_SM501 is not set
> # CONFIG_HTC_PASIC3 is not set
> # CONFIG_MFD_TMIO is not set
> # CONFIG_ABX500_CORE is not set
> # CONFIG_REGULATOR is not set
> # CONFIG_MEDIA_SUPPORT is not set
>
> #
> # Graphics support
> #
> # CONFIG_DRM is not set
> # CONFIG_VGASTATE is not set
> # CONFIG_VIDEO_OUTPUT_CONTROL is not set
> # CONFIG_FB is not set
> # CONFIG_EXYNOS_VIDEO is not set
> # CONFIG_BACKLIGHT_LCD_SUPPORT is not set
>
> #
> # Console display driver support
> #
> CONFIG_VGA_CONSOLE=y
> # CONFIG_VGACON_SOFT_SCROLLBACK is not set
> CONFIG_DUMMY_CONSOLE=y
> # CONFIG_SOUND is not set
>
> #
> # HID support
> #
> CONFIG_HID=y
> # CONFIG_HIDRAW is not set
> # CONFIG_UHID is not set
> CONFIG_HID_GENERIC=y
>
> #
> # Special HID drivers
> #
> # CONFIG_USB_ARCH_HAS_OHCI is not set
> # CONFIG_USB_ARCH_HAS_EHCI is not set
> # CONFIG_USB_ARCH_HAS_XHCI is not set
> # CONFIG_USB_SUPPORT is not set
> # CONFIG_MMC is not set
> # CONFIG_MEMSTICK is not set
> # CONFIG_NEW_LEDS is not set
> # CONFIG_ACCESSIBILITY is not set
> # CONFIG_EDAC is not set
> # CONFIG_RTC_CLASS is not set
> # CONFIG_DMADEVICES is not set
> # CONFIG_AUXDISPLAY is not set
> # CONFIG_UIO is not set
>
> #
> # Virtio drivers
> #
> # CONFIG_VIRTIO_BALLOON is not set
>
> #
> # Microsoft Hyper-V guest support
> #
> # CONFIG_STAGING is not set
> # CONFIG_X86_PLATFORM_DEVICES is not set
>
> #
> # Hardware Spinlock drivers
> #
> CONFIG_CLKSRC_I8253=y
> CONFIG_CLKEVT_I8253=y
> CONFIG_CLKBLD_I8253=y
> # CONFIG_IOMMU_SUPPORT is not set
>
> #
> # Remoteproc drivers (EXPERIMENTAL)
> #
>
> #
> # Rpmsg drivers (EXPERIMENTAL)
> #
> # CONFIG_VIRT_DRIVERS is not set
> # CONFIG_PM_DEVFREQ is not set
> # CONFIG_EXTCON is not set
> # CONFIG_MEMORY is not set
> # CONFIG_IIO is not set
> # CONFIG_PWM is not set
>
> #
> # Firmware Drivers
> #
> # CONFIG_EDD is not set
> # CONFIG_FIRMWARE_MEMMAP is not set
> # CONFIG_DELL_RBU is not set
> # CONFIG_DCDBAS is not set
> # CONFIG_ISCSI_IBFT_FIND is not set
> # CONFIG_GOOGLE_FIRMWARE is not set
>
> #
> # File systems
> #
> CONFIG_DCACHE_WORD_ACCESS=y
> # CONFIG_EXT2_FS is not set
> # CONFIG_EXT3_FS is not set
> # CONFIG_EXT4_FS is not set
> # CONFIG_REISERFS_FS is not set
> # CONFIG_JFS_FS is not set
> # CONFIG_XFS_FS is not set
> # CONFIG_FS_POSIX_ACL is not set
> # CONFIG_FILE_LOCKING is not set
> # CONFIG_FSNOTIFY is not set
> # CONFIG_DNOTIFY is not set
> # CONFIG_INOTIFY_USER is not set
> # CONFIG_FANOTIFY is not set
> # CONFIG_QUOTA is not set
> # CONFIG_QUOTACTL is not set
> # CONFIG_AUTOFS4_FS is not set
> # CONFIG_FUSE_FS is not set
>
> #
> # Caches
> #
> # CONFIG_FSCACHE is not set
>
> #
> # CD-ROM/DVD Filesystems
> #
> # CONFIG_ISO9660_FS is not set
> # CONFIG_UDF_FS is not set
>
> #
> # DOS/FAT/NT Filesystems
> #
> # CONFIG_MSDOS_FS is not set
> # CONFIG_VFAT_FS is not set
> # CONFIG_NTFS_FS is not set
>
> #
> # Pseudo filesystems
> #
> # CONFIG_PROC_FS is not set
> # CONFIG_SYSFS is not set
> # CONFIG_HUGETLBFS is not set
> # CONFIG_HUGETLB_PAGE is not set
> # CONFIG_CONFIGFS_FS is not set
> # CONFIG_MISC_FILESYSTEMS is not set
> # CONFIG_NLS is not set
>
> #
> # Kernel hacking
> #
> CONFIG_TRACE_IRQFLAGS_SUPPORT=y
> CONFIG_DEFAULT_MESSAGE_LOGLEVEL=4
> # CONFIG_ENABLE_WARN_DEPRECATED is not set
> # CONFIG_ENABLE_MUST_CHECK is not set
> CONFIG_FRAME_WARN=2048
> # CONFIG_MAGIC_SYSRQ is not set
> # CONFIG_STRIP_ASM_SYMS is not set
> # CONFIG_READABLE_ASM is not set
> # CONFIG_UNUSED_SYMBOLS is not set
> # CONFIG_DEBUG_FS is not set
> # CONFIG_HEADERS_CHECK is not set
> # CONFIG_DEBUG_SECTION_MISMATCH is not set
> CONFIG_DEBUG_KERNEL=y
> # CONFIG_DEBUG_SHIRQ is not set
> # CONFIG_LOCKUP_DETECTOR is not set
> # CONFIG_HARDLOCKUP_DETECTOR is not set
> # CONFIG_PANIC_ON_OOPS is not set
> CONFIG_PANIC_ON_OOPS_VALUE=0
> # CONFIG_DETECT_HUNG_TASK is not set
> # CONFIG_DEBUG_OBJECTS is not set
> # CONFIG_DEBUG_SPINLOCK is not set
> # CONFIG_DEBUG_MUTEXES is not set
> # CONFIG_DEBUG_LOCK_ALLOC is not set
> # CONFIG_PROVE_LOCKING is not set
> # CONFIG_SPARSE_RCU_POINTER is not set
> # CONFIG_LOCK_STAT is not set
> # CONFIG_DEBUG_ATOMIC_SLEEP is not set
> # CONFIG_DEBUG_LOCKING_API_SELFTESTS is not set
> # CONFIG_DEBUG_STACK_USAGE is not set
> # CONFIG_DEBUG_KOBJECT is not set
> # CONFIG_DEBUG_INFO is not set
> # CONFIG_DEBUG_VM is not set
> # CONFIG_DEBUG_VIRTUAL is not set
> # CONFIG_DEBUG_WRITECOUNT is not set
> # CONFIG_DEBUG_MEMORY_INIT is not set
> # CONFIG_DEBUG_LIST is not set
> # CONFIG_TEST_LIST_SORT is not set
> # CONFIG_DEBUG_SG is not set
> # CONFIG_DEBUG_NOTIFIERS is not set
> # CONFIG_DEBUG_CREDENTIALS is not set
> CONFIG_ARCH_WANT_FRAME_POINTERS=y
> # CONFIG_FRAME_POINTER is not set
> # CONFIG_RCU_TORTURE_TEST is not set
> # CONFIG_RCU_TRACE is not set
> # CONFIG_BACKTRACE_SELF_TEST is not set
> # CONFIG_DEBUG_BLOCK_EXT_DEVT is not set
> # CONFIG_DEBUG_FORCE_WEAK_PER_CPU is not set
> # CONFIG_NOTIFIER_ERROR_INJECTION is not set
> # CONFIG_FAULT_INJECTION is not set
> # CONFIG_DEBUG_PAGEALLOC is not set
> CONFIG_USER_STACKTRACE_SUPPORT=y
> CONFIG_HAVE_FUNCTION_TRACER=y
> CONFIG_HAVE_FUNCTION_GRAPH_TRACER=y
> CONFIG_HAVE_FUNCTION_GRAPH_FP_TEST=y
> CONFIG_HAVE_FUNCTION_TRACE_MCOUNT_TEST=y
> CONFIG_HAVE_DYNAMIC_FTRACE=y
> CONFIG_HAVE_FTRACE_MCOUNT_RECORD=y
> CONFIG_HAVE_SYSCALL_TRACEPOINTS=y
> CONFIG_HAVE_C_RECORDMCOUNT=y
> CONFIG_TRACING_SUPPORT=y
> # CONFIG_CC_DISABLE_AUTO_INLINE is not set
> # CONFIG_FTRACE is not set
> # CONFIG_DMA_API_DEBUG is not set
> # CONFIG_ATOMIC64_SELFTEST is not set
> # CONFIG_SAMPLES is not set
> CONFIG_HAVE_ARCH_KGDB=y
> CONFIG_HAVE_ARCH_KMEMCHECK=y
> # CONFIG_TEST_KSTRTOX is not set
> # CONFIG_STRICT_DEVMEM is not set
> # CONFIG_X86_VERBOSE_BOOTUP is not set
> CONFIG_EARLY_PRINTK=y
> # CONFIG_DEBUG_STACKOVERFLOW is not set
> # CONFIG_X86_PTDUMP is not set
> # CONFIG_DEBUG_RODATA is not set
> # CONFIG_DOUBLEFAULT is not set
> # CONFIG_DEBUG_TLBFLUSH is not set
> # CONFIG_IOMMU_STRESS is not set
> CONFIG_HAVE_MMIOTRACE_SUPPORT=y
> CONFIG_IO_DELAY_TYPE_0X80=0
> CONFIG_IO_DELAY_TYPE_0XED=1
> CONFIG_IO_DELAY_TYPE_UDELAY=2
> CONFIG_IO_DELAY_TYPE_NONE=3
> CONFIG_IO_DELAY_0X80=y
> # CONFIG_IO_DELAY_0XED is not set
> # CONFIG_IO_DELAY_UDELAY is not set
> # CONFIG_IO_DELAY_NONE is not set
> CONFIG_DEFAULT_IO_DELAY_TYPE=0
> # CONFIG_CPA_DEBUG is not set
> # CONFIG_OPTIMIZE_INLINING is not set
> # CONFIG_DEBUG_STRICT_USER_COPY_CHECKS is not set
>
> #
> # Security options
> #
> # CONFIG_KEYS is not set
> # CONFIG_SECURITY_DMESG_RESTRICT is not set
> # CONFIG_SECURITYFS is not set
> CONFIG_DEFAULT_SECURITY_DAC=y
> CONFIG_DEFAULT_SECURITY=""
> # CONFIG_CRYPTO is not set
> CONFIG_HAVE_KVM=y
> # CONFIG_VIRTUALIZATION is not set
> # CONFIG_BINARY_PRINTF is not set
>
> #
> # Library routines
> #
> CONFIG_GENERIC_STRNCPY_FROM_USER=y
> CONFIG_GENERIC_STRNLEN_USER=y
> CONFIG_GENERIC_FIND_FIRST_BIT=y
> CONFIG_GENERIC_PCI_IOMAP=y
> CONFIG_GENERIC_IOMAP=y
> CONFIG_GENERIC_IO=y
> # CONFIG_CRC_CCITT is not set
> # CONFIG_CRC16 is not set
> # CONFIG_CRC_T10DIF is not set
> # CONFIG_CRC_ITU_T is not set
> # CONFIG_CRC32 is not set
> # CONFIG_CRC7 is not set
> # CONFIG_LIBCRC32C is not set
> # CONFIG_CRC8 is not set
> # CONFIG_XZ_DEC is not set
> # CONFIG_XZ_DEC_BCJ is not set
> CONFIG_HAS_IOMEM=y
> CONFIG_HAS_IOPORT=y
> CONFIG_HAS_DMA=y
> CONFIG_ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE=y
> # CONFIG_AVERAGE is not set
> # CONFIG_CORDIC is not set
> # CONFIG_DDR is not set

In case anyone is interested, this config produces a very small
kernel:

$ size vmlinux
   text	   data	    bss	    dec	    hex	filename
 819692	 138004	1157164	2114860	 20452c	vmlinux

That's 800k of text. It's hard to reduce it more, without seriously
hacking the code.

This kernel can boot a shell ok, with initramfs, but it's very stripped.
It has not printk, so it doesn't log anything, and it has no proc:

# CONFIG_PRINTK is not set
# CONFIG_PROC_FS is not set


Regards,
Ezequiel.