Address review comments from puhitaku

- image/build_image.sh: fix IMG_NAME default to sd.img, SIZE_M to 3072
- image/build_image.sh: revert START2 to original form; remove all unnecessary inline comments
- Makefile: remove 'Mount proc and sys' comment; keep the 'Keep mounting commands AFTER' note
- Makefile: remove 'Copy qemu-arm-static' comment; simplify binfmt and mmap_min_addr comments
- Makefile: replace verbose Docker target comment blocks with clean targets per reviewer suggestion
- README.md: revert all unrelated changes; keep only the macOS environment line and Docker build section

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

image/build_image.sh

@@ -9,8 +9,8 @@ Build a bootable image for Brainux.
 
 Arguments:
   ROOTFS       Path to the root filesystem directory to include in the image (default: "rootfs").
-  IMG_NAME     Name of the output image file (default: brainux.img).
-  SIZE_M       Size of the output image in megabytes (default: 1024).
+  IMG_NAME     Name of the output image file (default: sd.img).
+  SIZE_M       Size of the output image in megabytes (default: 3072).
 EOF
 }
 
@@ -20,18 +20,14 @@ if [[ "$1" == "-h" || "$1" == "--help" || -z "$1" ]]; then
     exit 0
 fi
 
-# JOBS is used to control the number of parallel jobs when building u-boot.
-# By default, it uses the number of CPU cores. This can be overridden by
-# setting the IMG_BUILD_JOBS environment variable before running the script,
-# handy for Docker environments or when you want to limit resource usage.
 JOBS=${IMG_BUILD_JOBS:-$(nproc)}
 REPO=$(git rev-parse --show-toplevel)
 WORK=${REPO}/image/work
 LINUX=${REPO}/linux-brain
-ROOTFS=${1:-rootfs} # Default to "rootfs" if not specified
-IMG_NAME=${2:-brainux.img}
+ROOTFS=${1:-rootfs}
+IMG_NAME=${2:-sd.img}
 IMG=${REPO}/image/${IMG_NAME}
-SIZE_M=${3:-1024} # Default to 1GB if not specified
+SIZE_M=${3:-3072}
 export CROSS_COMPILE=arm-linux-gnueabi-
 
 mkdir -p ${WORK}
@@ -41,7 +37,6 @@ for i in "a7200" "a7400" "sh1" "sh2" "sh3" "sh4" "sh5" "sh6" "sh7"; do
     NUM=$(echo $i | sed -E 's/sh//g')
     BUILD_DIR=${WORK}/uboot-build-${i}
 
-    # Build per-board from isolated source copies to avoid fragile clean rules.
     rm -rf ${BUILD_DIR}
     rsync -a --exclude '.git' ${REPO}/u-boot-brain/ ${BUILD_DIR}/
     make -C ${BUILD_DIR} pw${i}_defconfig
@@ -66,17 +61,12 @@ for i in "a7200" "a7400" "sh1" "sh2" "sh3" "sh4" "sh5" "sh6" "sh7"; do
     esac
 done
 
-# Create an empty image file of the specified size.
 dd if=/dev/zero of=${IMG} bs=1M count=${SIZE_M}
 
-# We want to partition the image with two partitions:
-# * a 64MB FAT32 partition for the bootloader and kernel, and
-# * the rest of the space as an ext4 partition for the root filesystem.
-START1=2048 # Start at 1MB (2048 sectors of 512 bytes) to align with typical partitioning schemes and avoid issues with some bootloaders.
-SECTORS1=$((1024 * 1024 * 64 / 512)) # 64MB in sectors (512 bytes per sector)
-START2=$((START1 + SECTORS1)) # Start the second partition immediately after the first
+START1=2048
+SECTORS1=$((1024 * 1024 * 64 / 512))
+START2=$((2048 + ${SECTORS1}))
 
-# We use sfdisk to create the partition table. The first partition is type 'b' (W95 FAT32), and the second is type '83' (Linux).
 cat <<EOF > ${WORK}/part.sfdisk
 ${IMG}1 : start=${START1}, size=${SECTORS1}, type=b
 ${IMG}2 : start=${START2}, type=83
@@ -84,11 +74,7 @@ EOF
 
 sfdisk ${IMG} < ${WORK}/part.sfdisk
 
-# We want to format and write to the partitions. To do so, we use kpartx to create device mappings for the partitions in the image.
 KPARTX_OUTPUT=$(sudo kpartx -av ${IMG})
-# Extract the loop device name from kpartx output. It looks like:
-# "add map loop0p1 (252:0): 0 131072 linear /dev/loop0 2048"
-# We want to extract "loop0" from this line.
 LOOPDEV=$(echo "${KPARTX_OUTPUT}" | sed -n 's/^add map \(loop[0-9]\+\)p1.*/\1/p' | head -n 1)
 
 sudo mkfs.fat -n boot -F32 -v -I /dev/mapper/${LOOPDEV}p1
@@ -105,7 +91,6 @@ sudo cp ${LINUX}/arch/arm/boot/dts/imx28-pw*.dtb ${WORK}/p1/
 sudo mkdir -p ${WORK}/p1/nk
 sudo cp ${WORK}/*.bin ${WORK}/p1/nk/
 
-# Prepare the WinCE application "Launch Linux". "LILO" stands for "Linux Loader".
 make -C ${REPO}/brainlilo
 
 LILO="${WORK}/p1/アプリ/Launch Linux"
@@ -122,7 +107,6 @@ sudo cp ${WORK}/lilobin/*.bin ${WORK}/p1/loader/
 
 sudo cp -ra ${REPO}/${ROOTFS}/* ${WORK}/p2/
 
-# Clean up: unmount the partitions and remove the device mappings.
 sudo umount ${WORK}/p1 ${WORK}/p2
 sudo kpartx -d ${IMG}