Mengembalikan Ubuntu yang Hilang Setelah Install Windows 10

Laptop saya sebelumnya sudah terinstal Ubuntu 16.04. Kemudian saya ada kebutuhan untuk memakai Windows juga. Maka saya buat satu partisi lagi untuk Windows. Windows 10 berhasil di-install dengan baik. Tapi saya terkaget-kaget mendapati bahwa partisi di mana Ubuntu ter-install menjadi unallocated. Jadi Ubuntu nya tidak bisa diakses lagi!

Namun saya menemukan solusi nya di sini.

https://askubuntu.com/questions/828838/installed-windows-10-grub-problem-linux-drive-became-unallocated

Di posting itu ada link di bawah ini, dan command di situ yang saya ikuti:

https://askubuntu.com/questions/665445/upgraded-to-windows-10-on-dual-boot-and-cant-boot-to-ubuntu-partition/665462

Partisi Ubuntu yang ‘hilang’ ini terjadi karena sewaktu instalasi Windows, Windows mengubah Master Boot Record (MBR) harddisk dengan cara yang tidak benar. Sebetulnya isi data dalam partisi Ubuntu tersebut tidak tersentuh sama sekali. Yang rusak adalah informasi identitas partisi tersebut dalam tabel MBR. Sehingga partisi tersebut jadi tidak dikenali.

Sebab itu kita perlu memasukkan lagi informasi partisi Ubuntu tersebut ke dalam tabel MBR. Solusinya menggunakan tool bernama parted, dan dijalankan melalui command prompt Linux.

Langkah pertama siapkan flashdisk Ubuntu Live dari Windows . Ikuti langkah-langkahnya di sini:

https://itsfoss.com/create-live-usb-of-ubuntu-in-windows/

Setelah menyiapkan Ubuntu Live, booting lah melalui flashdisk tersebut dan pilih mode Ubuntu Live (tanpa meng-install).

Kemudian buka command prompt dalam masukkan command

> sudo parted
> unit s
> print all
> rescue [start] [end]

Ganti [start] dan [end] dengan angka sector di mana terdapat partisi Ubuntu yang ‘hilang’.

Saya tidak sempat membuat screenshot dari proses di atas. Saya coba ilustrasikan pakai Ubuntu yang sudah berhasil dikembalikan. Kurang lebih akan seperti screenshot di bawah ini:

parted-edit

Setelah menjalan perintah rescue, akan muncul pesan bahwa ditemukan file system ext4 (atau yang lainnya sesuai partisi Anda) dan akan ditambahkan pada tabel MBR.

Anda bisa jalankan perintah print all lagi, dan lihat bahwa partisi yang hilang telah ditemukan kembali!

Setelah ini, saya menggunakan tool EasyBCD pada Windows untuk menambahkan Ubuntu pada list OS pada saat booting Windows. Langkah-langkah bisa dilihat di sini. EasyBCD bisa di-download di sini. Pilih yang Non-Commercial (free).

Selain menggunakan EasyBCD pada Windows, Anda bisa juga menggunakan tool boot-repair dalam Ubuntu Live lagi. Langkah-langkahnya bisa dilihat di sini. Namun saya sendiri tidak mencobanya.

Selamat atas kembalinya Ubuntu!

[Raspberry Pi] Installing piCore 9.0

At this moment, I have played with my Raspberry Pi B for quite some time. Instead of using the standard Raspbian Jessie OS, I am curious about running alternative OS. I am looking for something much simpler than the full featured Raspbian Jessie. The reason I am doing this is because I want to comprehend the internal working of embedded Linux. I aim to understand the detail processes of building the Linux OS, and steps involved from power-on, running user apps, until power-off. I suppose the simpler the system, the easier to learn. Back to the alternative OS, it should be lightweight and fast to boot up. One of the options that I encounter — and looks promising — is piCore. It is the Raspberry Pi porting of TinyCore OS.

Here I describe how I install piCore 9.0 on my Raspberry Pi B. piCore-9.0.zip compressed image is downloaded from here. Extract it and you will have a 51.4 MB piCore image. According to the official installation guide the image can be extracted directly on SD Card using dd command on Linux or Win32 Disk Imager on Windows. However, my SD card already contains the Raspbian Jessie (using NOOBS image), and I still want to keep it there. So, I am trying to copy the image contents manually in a way that the Raspbian sits still on my SD Card. Later, I can revert back to the Raspbian Jessie. This workaround will just work because of the booting  mechanisms of NOOBS installation. A nice explanation can be found here.

First, go to the directory containing the image and issue fdisk -l piCore-9.0.img command to list the partitions and its corresponding start sector.

Disk piCore-9.0.img: 49 MiB, 51380224 bytes, 100352 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x0009bf4f

Device          Boot Start    End Sectors Size Id Type
piCore-9.0.img1       8192  77823   69632  34M  c W95 FAT32 (LBA)
piCore-9.0.img2      77824 100351   22528  11M 83 Linux

It can be seen that the unit sector size is 512 bytes, and there are two images. So, create two directories for mounting those two images, let’s say: mkdir picore_1 and picore_2. Then mount the images on the created directories:

sudo mount -o loop,offset=$((512*8192)) piCore-9.0.img ./picore_1
sudo mount -o loop,offset=$((77824*8192)) piCore-9.0.img ./picore_2

picore_1 contains the Linux kernel, Device Tree Blobs, initramfs, and booting parameters. All of them will be copied in the /boot partition on my SD Card. But, before copying, I have created a directory /boot/rpi-boot and moved all the exisiting files in /boot to /boot/rpi-boot. By doing so, I can still use the Raspian OS in the future by moving them back into the parent directory, i.e. /boot.

picore_2 only contains a single tce directory. It is copied to /root partition on my SD Card. Now, the SD Card can be put on the Raspberry Pi, and power-on the board. If everything goes well, piCore will boot into command line mode. To install TC desktop packages, issue: tce-load -wi TC. It will download all necessary packages from the repository. Surely, this assumes that internet access has been provided via LAN connection. After downloading has finished, issue command filetool.sh -b to make all settings persistent. So the settings will be automatically loaded on next boots.Now, we can fire up the desktop mode by issuing startx.

Next time we reboot piCore it will automatically go into desktop mode. The video below shows the piCore booting on my Raspberry Pi B. Note that I have enabled showapps boot parameter in /boot/cmdline.txt so that the loaded modules get printed on the screen. It is surprising to me that the overall booting time is not faster than that of Raspbian OS. It is even slower, I think.

At the time of this writing, available apps ported to piCore are still very limited. The only web browser you can install is Dillo 3. Not much can be explored as an end-user. Previously I am thinking to run Firefox or Chromium to compare the performance when run in Raspbian OS, since piCore is advertised to be fast due to its operation that is fully run in RAM.

I also compare the content of /boot partition of Raspbian Jessie and piCore. I found out that there is no initramfs in the Raspbian Jessie. I suppose it is bundled into the kernel image.

It is worth to mention that for unknown reasons sometimes the extended modules do not get loaded during boot-up. And no information whatsoever is spilled out to notify this situation. It try to change the boot parameter to waitusb=5 for example, to give (indirectly) time for the SD Card to get ready. Although I have not done an exhausted test, but it seems to work. Still, I am not sure whether it is the root of cause.

In the meantime, I am still running buildroot to automate the building process of another Linux (official RPi) for my Raspberry Pi. It does take a long time since all the source codes are downloaded from the repositories and then get compiled. Can’t wait to see the result!