Fix instructions

Author: Mitchell Levy

README.md

@@ -24,7 +24,7 @@ request, we encourage you to [submit the change upstream][submit-patch].
 
 # Build Instructions
 
-Instructions for building an x86_64 WSL2 kernel with an Ubuntu distribution are
+Instructions for building an x86_64 WSL2 kernel with an Ubuntu distribution using bash are
 as follows:
 
 1. Install the build dependencies:  
@@ -39,23 +39,23 @@ as follows:
 
    You may wish to include `-j$(nproc)` on the first `make` command to build in parallel.
 
-4. Calculate the modules size (plus 1024 bytes for slack):
-   `modules_size=$(du -s "$PWD/modules" | awk '{print $1;}'); modules_size=$((modules_size + 1024));`
+4. Calculate the modules size (plus 256 MB for slack):
+   `modules_size=$(du -bs "$PWD/modules" | awk '{print $1;}'); modules_size=$((modules_size + (256*(1<<20))));`
 
 5. Create a blank image file for the modules:
-   `dd if=/dev/zero of="$PWD/modules.img" bs=1 count=$modules_size`
+   `dd if=/dev/zero of="$PWD/modules.img" bs=1024 count=$((modules_size / 1024))`
 
 6. Setup filesystem and mount img file:
-   `lo_dev=$(losetup --find --show "$PWD/modules.img"); mkfs -t ext4 $lo_dev; sudo mount $lo_dev "$PWD/modules_img"`
+   `lo_dev=$(sudo losetup --find --show "$PWD/modules.img"); sudo mkfs -t ext4 $lo_dev; mkdir $PWD/modules_img; sudo mount $lo_dev "$PWD/modules_img"; sudo chmod a+w "$PWD/modules_img"`
 
 7. Copy over the modules, unmount the img now that we're done with it:
-   `cp -r "$PWD/modules/lib/modules/$(make -s kernelrelease)" "$PWD/modules_img"; sudo umount "$PWD/modules_img"`
+   `cp -r "$PWD/modules/lib/modules/$(make -s kernelrelease)"/* "$PWD/modules_img"; sudo umount "$PWD/modules_img"`
 
 8. Convert the img to VHDX:
-   `qemu-img convert -O VHDX "$PWD/modules.img" "$PWD/modules.vhdx"`
+   `qemu-img convert -O vhdx "$PWD/modules.img" "$PWD/modules.vhdx"`
 
 9. Clean up:
-   `rm modules.img # optionally $PWD/modules dir too`
+   `rm -r modules.img modules_img # optionally $PWD/modules dir too`
 
 # Install Instructions