plembo · October 9, 2025 02:52 · Mar 5, 2025 · Apr 5, 2022 · Apr 5, 2022 · Aug 6, 2018
diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -18,12 +18,10 @@ missing key information.
 with arm processors like the Pi.
 2. Create an emulation project directory, "~/Projects/rpitest" to hold the emulation files.
 3. Clone the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) repo to another directory using git.
-4. Follow the instructions in the repo for building a versatile-pb.dtb file for your kernel of choice
-(or simply use the kernel and matching .dtb file provided by default -- currently kernel-4.9.41-stretch).
-5. Copy the kernel image and matching versatile-pb.dtb file into the project directory (e.g. "rpitest").
+4. Copy the kernel image and matching versatile-pb.dtb file into the project directory (e.g. "rpitest").
 Rename the kernel file to "kernel-qemu".
-6. Download the latest Raspbian disk image and unzip into the project directory.
-7. Find starting sector of the image's second partition using fdisk:
+5. Download the latest Raspbian disk image and unzip into the project directory.
+6. Find starting sector of the image's second partition using fdisk:
 
 ```bash
 $ fdisk -l 2018-06-27-raspbian-stretch.img

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -53,7 +53,7 @@ This will enable devices like keyboards and mice to work in the emulator.
 
 10. Unmount and rename the file to "rpitest.img".
 ```
-$ sudo umount 2018-06-27-raspbian-stretch.img
+$ sudo umount /mnt
 $ mv 2018-06-27-raspbian-stretch.img rpitest.img
 ```
 12. Convert the raw img file to qcow2 format:

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -26,7 +26,7 @@ Rename the kernel file to "kernel-qemu".
 7. Find starting sector of the image's second partition using fdisk:
 
 ```bash
-fdisk -l 2018-06-27-raspbian-stretch.img
+$ fdisk -l 2018-06-27-raspbian-stretch.img
 Disk 2018-06-27-raspbian-stretch.img: 4.5 GiB, 4823449600 bytes, 9420800 sectors
 Units: sectors of 1 * 512 = 512 bytes
 Sector size (logical/physical): 512 bytes / 512 bytes
@@ -42,27 +42,31 @@ Device                           Boot Start     End Sectors  Size Id Type
 image:
 
 ```bash
-sudo mount 2018-06-27-raspbian-stretch.img -o offset=50331648 /mnt
+$ sudo mount 2018-06-27-raspbian-stretch.img -o offset=50331648 /mnt
 ```
 9. Edit the ld.so.preload file to comment out its one and only line:
 
 ```
-sudo vi /mnt/etc/ld.so.preload
+$ sudo vi /mnt/etc/ld.so.preload
 ```
 This will enable devices like keyboards and mice to work in the emulator.
 
 10. Unmount and rename the file to "rpitest.img".
-11. Convert the raw img file to qcow2 format:
+```
+$ sudo umount 2018-06-27-raspbian-stretch.img
+$ mv 2018-06-27-raspbian-stretch.img rpitest.img
+```
+12. Convert the raw img file to qcow2 format:
 ```bash
-qemu-img convert -f raw -O qcow2 rpitest.img rpitest.qcow2
+$ qemu-img convert -f raw -O qcow2 rpitest.img rpitest.qcow2
 ```
 
 ## Starting the virtual machine
 Copy the following code into a startup script called something like "rpistart.sh":
 
 ```bash
 #!/usr/bin/env bash
-sudo qemu-system-arm -kernel kernel-qemu \
+$ sudo qemu-system-arm -kernel kernel-qemu \
 -cpu arm1176 -m 256 \
 -M versatilepb -dtb versatile-pb.dtb \
 -no-reboot \
@@ -85,13 +89,13 @@ to be expanded in size. The following steps will accomplish that.
 
 1. Shut down the virtual machine and run qemu-img to increase the disk size:
 ```
-qemu-img resize rpitest.qcow2 +4G
+$ qemu-img resize rpitest.qcow2 +4G
 ```
 
 2. Start up the machine again and log in. Run fdisk to delete and then re-create
 the second partition.
 ```
-sudo fdisk /dev/sda
+$ sudo fdisk /dev/sda
 ```
 The commands to run within fdisk are:
 
@@ -113,7 +117,7 @@ w - to write all changes to disk
 
 3. Complete the resizing operation by running resize2fs on the partition:
 ```bash
-resize2fs /dev/sda2
+$ resize2fs /dev/sda2
 ```
 4. Run df -h to confirm the expanded disk size is recognized by the system.
 
diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -2,6 +2,9 @@
 Goal: Emulate a [Raspberry Pi](https://www.raspberrypi.org/) with [QEMU](https://www.qemu.org/)
 in order to run the [Raspbian O/S](https://www.raspberrypi.org/downloads/raspbian/) (based on Debian Linux).
 
+The current setup is not ideal. For one thing, the maximum RAM allowed using the "versatile-pb" firmware is
+256 Mb. In addition, only the most basic peripherals, a keyboard and mouse, are supported.
+
 A number of articles have been written on this topic. Most are outdated, and the few recent ones are
 missing key information.
 

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -13,12 +13,12 @@ missing key information.
 ## Procedure
 1. Install qemu-system-arm (on Ubuntu, "sudo apt-get qemu-system-arm") to allow the emulation of devices
 with arm processors like the Pi.
-2. Create an emulation project directory, like "rpitest" to hold the emulation files.
+2. Create an emulation project directory, "~/Projects/rpitest" to hold the emulation files.
 3. Clone the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) repo to another directory using git.
 4. Follow the instructions in the repo for building a versatile-pb.dtb file for your kernel of choice
 (or simply use the kernel and matching .dtb file provided by default -- currently kernel-4.9.41-stretch).
-5. Copy the kernel image and matching .dtb file into the project directory (e.g. "rpitest"). Rename the kernel
-file to "kernel-qemu".
+5. Copy the kernel image and matching versatile-pb.dtb file into the project directory (e.g. "rpitest").
+Rename the kernel file to "kernel-qemu".
 6. Download the latest Raspbian disk image and unzip into the project directory.
 7. Find starting sector of the image's second partition using fdisk:
 

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -17,7 +17,8 @@ with arm processors like the Pi.
 3. Clone the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) repo to another directory using git.
 4. Follow the instructions in the repo for building a versatile-pb.dtb file for your kernel of choice
 (or simply use the kernel and matching .dtb file provided by default -- currently kernel-4.9.41-stretch).
-5. Copy the kernel image and matching .dtb file into the project directory (e.g. "rpitest").
+5. Copy the kernel image and matching .dtb file into the project directory (e.g. "rpitest"). Rename the kernel
+file to "kernel-qemu".
 6. Download the latest Raspbian disk image and unzip into the project directory.
 7. Find starting sector of the image's second partition using fdisk:
 
@@ -47,7 +48,7 @@ sudo vi /mnt/etc/ld.so.preload
 ```
 This will enable devices like keyboards and mice to work in the emulator.
 
-10. Unmount and rename the file to something short, like rpitest.img.
+10. Unmount and rename the file to "rpitest.img".
 11. Convert the raw img file to qcow2 format:
 ```bash
 qemu-img convert -f raw -O qcow2 rpitest.img rpitest.qcow2

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -16,7 +16,7 @@ with arm processors like the Pi.
 2. Create an emulation project directory, like "rpitest" to hold the emulation files.
 3. Clone the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) repo to another directory using git.
 4. Follow the instructions in the repo for building a versatile-pb.dtb file for your kernel of choice
-(or simply use the kernel and matching .dtb file provided by default).
+(or simply use the kernel and matching .dtb file provided by default -- currently kernel-4.9.41-stretch).
 5. Copy the kernel image and matching .dtb file into the project directory (e.g. "rpitest").
 6. Download the latest Raspbian disk image and unzip into the project directory.
 7. Find starting sector of the image's second partition using fdisk:

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -11,9 +11,10 @@ missing key information.
 3. Latest Debian Stretch kernel from the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) project.
 
 ## Procedure
-1. Install qemu-system-arm (on Ubuntu, "sudo apt-get qemu-system-arm").
-2. Create an emulation project directory, like "rpitest".
-3. Clone the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) repo using git.
+1. Install qemu-system-arm (on Ubuntu, "sudo apt-get qemu-system-arm") to allow the emulation of devices
+with arm processors like the Pi.
+2. Create an emulation project directory, like "rpitest" to hold the emulation files.
+3. Clone the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) repo to another directory using git.
 4. Follow the instructions in the repo for building a versatile-pb.dtb file for your kernel of choice
 (or simply use the kernel and matching .dtb file provided by default).
 5. Copy the kernel image and matching .dtb file into the project directory (e.g. "rpitest").
@@ -44,10 +45,10 @@ sudo mount 2018-06-27-raspbian-stretch.img -o offset=50331648 /mnt
 ```
 sudo vi /mnt/etc/ld.so.preload
 ```
-10. Unmount and rename the file to something short, like rpitest.img.
+This will enable devices like keyboards and mice to work in the emulator.
 
+10. Unmount and rename the file to something short, like rpitest.img.
 11. Convert the raw img file to qcow2 format:
-
 ```bash
 qemu-img convert -f raw -O qcow2 rpitest.img rpitest.qcow2
 ```
@@ -69,8 +70,14 @@ sudo qemu-system-arm -kernel kernel-qemu \
 ```
 Login using username "pi" and password "raspberry".
 
+Your machine should be fully functional at this point, and able to reach the Internet over
+the virtual network (vnet0) created along with it.
+
+Do not update the system at this point, as the shipping image is 97% full.
+
 ## Expand the disk size
-This is necessary because the shipping image is 97% full.
+To update and do useful work with the system, the root partition (/dev/sda2) will need
+to be expanded in size. The following steps will accomplish that.
 
 1. Shut down the virtual machine and run qemu-img to increase the disk size:
 ```

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -14,7 +14,8 @@ missing key information.
 1. Install qemu-system-arm (on Ubuntu, "sudo apt-get qemu-system-arm").
 2. Create an emulation project directory, like "rpitest".
 3. Clone the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) repo using git.
-4. Follow the instructions in the repo for building a versatile-pb.dtb file for your kernel of choice.
+4. Follow the instructions in the repo for building a versatile-pb.dtb file for your kernel of choice
+(or simply use the kernel and matching .dtb file provided by default).
 5. Copy the kernel image and matching .dtb file into the project directory (e.g. "rpitest").
 6. Download the latest Raspbian disk image and unzip into the project directory.
 7. Find starting sector of the image's second partition using fdisk:
@@ -76,7 +77,7 @@ This is necessary because the shipping image is 97% full.
 qemu-img resize rpitest.qcow2 +4G
 ```
 
-2. While logged into the virtual machine, run fdisk to delete and then re-create
+2. Start up the machine again and log in. Run fdisk to delete and then re-create
 the second partition.
 ```
 sudo fdisk /dev/sda

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -71,7 +71,12 @@ Login using username "pi" and password "raspberry".
 ## Expand the disk size
 This is necessary because the shipping image is 97% full.
 
-1. While logged into the virtual machine, run fdisk to delete and then re-create
+1. Shut down the virtual machine and run qemu-img to increase the disk size:
+```
+qemu-img resize rpitest.qcow2 +4G
+```
+
+2. While logged into the virtual machine, run fdisk to delete and then re-create
 the second partition.
 ```
 sudo fdisk /dev/sda
@@ -94,9 +99,9 @@ Enter - to accept the last sector of the disk as the end of the partition
 w - to write all changes to disk
 ```
 
-2. Complete the resizing operation by running resize2fs on the partition:
+3. Complete the resizing operation by running resize2fs on the partition:
 ```bash
 resize2fs /dev/sda2
 ```
-3. Run df -h to confirm the expanded disk size is recognized by the system.
+4. Run df -h to confirm the expanded disk size is recognized by the system.
 
diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -58,7 +58,7 @@ Copy the following code into a startup script called something like "rpistart.sh
 #!/usr/bin/env bash
 sudo qemu-system-arm -kernel kernel-qemu \
 -cpu arm1176 -m 256 \
- -M versatilepb -dtb versatile-pb.dtb \
+-M versatilepb -dtb versatile-pb.dtb \
 -no-reboot \
 -serial stdio \
 -append "root=/dev/sda2 panic=1 rootfstype=ext4 rw" \

diff --git a/RPIwithQEMU.md b/RPIwithQEMU.md
@@ -0,0 +1,102 @@
+# Emulating a Raspberry Pi with QEMU
+Goal: Emulate a [Raspberry Pi](https://www.raspberrypi.org/) with [QEMU](https://www.qemu.org/)
+in order to run the [Raspbian O/S](https://www.raspberrypi.org/downloads/raspbian/) (based on Debian Linux).
+
+A number of articles have been written on this topic. Most are outdated, and the few recent ones are
+missing key information.
+
+## Software Required
+1. QEMU system emulation binaries for ARM processors. On Ubuntu, qemu-system-arm.
+2. [Raspbian Stretch with Desktop](https://downloads.raspberrypi.org/raspbian_latest), disk image.
+3. Latest Debian Stretch kernel from the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) project.
+
+## Procedure
+1. Install qemu-system-arm (on Ubuntu, "sudo apt-get qemu-system-arm").
+2. Create an emulation project directory, like "rpitest".
+3. Clone the [qemu-rpi-kernel](https://github.com/dhruvvyas90/qemu-rpi-kernel) repo using git.
+4. Follow the instructions in the repo for building a versatile-pb.dtb file for your kernel of choice.
+5. Copy the kernel image and matching .dtb file into the project directory (e.g. "rpitest").
+6. Download the latest Raspbian disk image and unzip into the project directory.
+7. Find starting sector of the image's second partition using fdisk:
+
+```bash
+fdisk -l 2018-06-27-raspbian-stretch.img
+Disk 2018-06-27-raspbian-stretch.img: 4.5 GiB, 4823449600 bytes, 9420800 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: 0xbd98648d
+
+Device                           Boot Start     End Sectors  Size Id Type
+2018-06-27-raspbian-stretch.img1       8192   96663   88472 43.2M  c W95 FAT32 (LBA)
+2018-06-27-raspbian-stretch.img2      98304 9420799 9322496  4.5G 83 Linux
+```
+8. Multiply that sector number by 512 and use the result as the offset in mounting the
+image:
+
+```bash
+sudo mount 2018-06-27-raspbian-stretch.img -o offset=50331648 /mnt
+```
+9. Edit the ld.so.preload file to comment out its one and only line:
+
+```
+sudo vi /mnt/etc/ld.so.preload
+```
+10. Unmount and rename the file to something short, like rpitest.img.
+
+11. Convert the raw img file to qcow2 format:
+
+```bash
+qemu-img convert -f raw -O qcow2 rpitest.img rpitest.qcow2
+```
+
+## Starting the virtual machine
+Copy the following code into a startup script called something like "rpistart.sh":
+
+```bash
+#!/usr/bin/env bash
+sudo qemu-system-arm -kernel kernel-qemu \
+-cpu arm1176 -m 256 \
+ -M versatilepb -dtb versatile-pb.dtb \
+-no-reboot \
+-serial stdio \
+-append "root=/dev/sda2 panic=1 rootfstype=ext4 rw" \
+-hda rpitest.qcow2 \
+-net nic -net user \
+-net tap,ifname=vnet0,script=no,downscript=no
+```
+Login using username "pi" and password "raspberry".
+
+## Expand the disk size
+This is necessary because the shipping image is 97% full.
+
+1. While logged into the virtual machine, run fdisk to delete and then re-create
+the second partition.
+```
+sudo fdisk /dev/sda
+```
+The commands to run within fdisk are:
+
+```
+print - to show the current disk layout
+```
+(note the starting sector of the second partition)
+
+```
+d - to delete a partition
+2 - choose partition 2
+n - create a new partition
+p - make it primary
+2 - partition number
+xxxxx - the starting sector of the original partition 2
+Enter - to accept the last sector of the disk as the end of the partition
+w - to write all changes to disk
+```
+
+2. Complete the resizing operation by running resize2fs on the partition:
+```bash
+resize2fs /dev/sda2
+```
+3. Run df -h to confirm the expanded disk size is recognized by the system.
+
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