commit b2ab5b464dcf597f1788d812405b8cba8b23e06e
parent a1a80feeea22dcc910b8fcd7dd3d9a5f82d716b2
Author: Georges Dupéron <georges.duperon@gmail.com>
Date: Sun, 8 Jul 2018 22:12:00 +0200
Chameleon: the OS is now also a GPT-partitioned disk image (with a small quirk)
The quirk is that the ZIP trailer is inserted after the end of the
GPT-partitioned space, but GPT normally covers the whole disk.
This image is intended to be burned on a CD, flashed onto a floppy, USB key or
SD card. In these last two cases (where the GPT would make sense), the end of
the disk cannot be known in advance, so an incorrectly-placed GPT mirror is
not quite unexpected.
Diffstat:
3 files changed, 89 insertions(+), 38 deletions(-)
diff --git a/example-os/.gitignore b/example-os/.gitignore
@@ -12,5 +12,8 @@
/os.32k
/os.fat12
/os.offsets
+/os.hex_with_offsets
/iso_files/os.zip
/iso_files/boot/iso_boot.sys
+/build/offsets/fat12_start.hex
+/build/offsets/fat12_start.dec
diff --git a/example-os/Makefile b/example-os/Makefile
@@ -1,7 +1,10 @@
os_filename = os.bat
-tests = test/qemu-system-i386-floppy test/qemu-system-i386-cdrom test/qemu-system-arm test/virtualbox test/bochs test/gui-sh test/dosbox
-built_files = $(os_filename) os.ndisasm.disasm os.reasm.asm os.reasm os.reasm.disasm os.file os.fdisk os.arm.disasm os.zip os.zip.adjusted os.iso os.32k os.fat12 os.offsets iso_files/os.zip iso_files/boot/iso_boot.sys
-built_directories = iso_files/boot iso_files
+tests_emu = test/qemu-system-i386-floppy test/qemu-system-i386-cdrom test/qemu-system-arm test/virtualbox test/bochs test/gui-sh test/dosbox
+tests_requiring_sudo = test/fat12_mount test/iso_mount
+tests_noemu = test/zip os.reasm test/sizes test/fat12_contents
+built_files = $(os_filename) os.ndisasm.disasm os.reasm.asm os.reasm os.reasm.disasm os.file os.fdisk os.arm.disasm os.zip os.zip.adjusted os.iso os.32k os.fat12 os.offsets os.hex_with_offsets iso_files/os.zip iso_files/boot/iso_boot.sys build/offsets/fat12_start.hex build/offsets/fat12_start.dec
+# TODO: auto-add the .dec files for each .hex offset.
+built_directories = iso_files/boot iso_files build/offsets build/mnt_fat12 build/mnt_iso build
os_image_size_kb = 1440
os_partition_start_sectors = 3
@@ -12,12 +15,14 @@ os_floppy_chs_s = 9
.PHONY: all
# all: os.arm.disasm
-all: $(os_filename) os.ndisasm.disasm os.reasm.asm os.file os.fdisk os.offsets .gitignore Makefile
+all: $(os_filename) os.ndisasm.disasm os.reasm.asm os.file os.fdisk os.offsets os.hex_with_offsets .gitignore Makefile
-../deploy-screenshots: Makefile
+../deploy-screenshots $(built_directories): Makefile
mkdir -p $@
touch $@
+iso_files/boot: iso_files
+
# 32k header of the ISO9660 image
os.32k: os.asm Makefile
nasm -o $@ $<
@@ -35,8 +40,11 @@ os.iso: iso_files/os.zip iso_files/boot/iso_boot.sys Makefile
-output os.iso \
./iso_files/
+# Layout:
+# MBR; GPT; UNIX sh & MS-DOS batch scripts; ISO9660; FAT12; GPT mirror; ZIP
+
sector_size = 512
-# should be exact
+# should be exact (TODO: make a check)
os_total_size_sectors = ( $(os_image_size_kb)*1024 / $(sector_size) )
os_total_size_tracks = ( $(os_total_size_sectors) / $(os_floppy_chs_s) )
# round up
@@ -45,8 +53,10 @@ iso_size_tracks = ( ( $(iso_size_sectors) + $(os_floppy_chs_s) - 1 ) / $(os_flop
# round up
zip_size_sectors = ( ( $$(wc -c os.zip | cut -d ' ' -f 1) + $(sector_size) - 1 ) / $(sector_size) )
zip_size_tracks = ( ( $(zip_size_sectors) + $(os_floppy_chs_s) - 1 ) / $(os_floppy_chs_s) )
+gpt_mirror_size_sectors = 33
+gpt_mirror_size_tracks = ( ( $(gpt_mirror_size_sectors) + $(os_floppy_chs_s) - 1 ) / $(os_floppy_chs_s) )
# allocate the remaining sectors, aligned on tracks
-fat12_size_tracks = ( ( $(os_total_size_tracks) - $(iso_size_tracks) - $(zip_size_tracks) ) )
+fat12_size_tracks = ( ( $(os_total_size_tracks) - $(iso_size_tracks) - $(gpt_mirror_size_tracks) - $(zip_size_tracks) ) )
fat12_size_sectors = ( $(fat12_size_tracks) * $(os_floppy_chs_s) )
# zip should probably have its end aligned, not its start
space_before_zip_bytes = ( $(os_image_size_kb)*1024 - $$(wc -c os.zip | cut -d ' ' -f 1) )
@@ -61,6 +71,9 @@ iso_end = ( $(iso_size_sectors) * $(sector_size) )
fat12_start = ( $(iso_size_tracks) * $(os_floppy_chs_s) * $(sector_size) )
fat12_size = ( $(fat12_size_sectors) * $(sector_size) )
fat12_end = ( $(fat12_start) + $(fat12_size) )
+# It is probably not necessary to align the GPT mirror end on a track boundary.
+gpt_mirror_end = ( $(fat12_end) + ( $(gpt_mirror_size_tracks) * $(os_floppy_chs_s) * $(sector_size) ) )
+gpt_mirror_start = ( $(gpt_mirror_end) - ( $(gpt_mirror_size_sectors) * $(sector_size) ) )
zip_start = $(space_before_zip_bytes)
zip_end = ( $(os_total_size_sectors) * $(sector_size) )
@@ -74,12 +87,6 @@ os.fat12: os.zip os.iso Makefile
-i $(os_fat12_partition)
set -x; mcopy -i $(os_fat12_partition) os.zip "::os.zip"
-iso_files: Makefile
- mkdir -p $@
-
-iso_files/boot: iso_files Makefile
- mkdir -p $@
-
iso_files/os.zip: os.zip iso_files Makefile
# TODO: make it so that the various file formats are mutual quines:
# * the ISO should contain the original file
@@ -107,10 +114,15 @@ $(os_filename): os.32k os.iso os.fat12 os.zip os.zip.adjusted ../deploy-screensh
set -x; dd skip=$$(( $(header_32k_start) )) seek=$$(( $(header_32k_start) )) bs=1 count=$$(( $(header_32k_size) )) conv=notrunc if=os.32k of=$@
# splice in fat12
set -x; dd skip=$$(( $(fat12_start) )) seek=$$(( $(fat12_start) )) bs=1 count=$$(( $(fat12_size) )) conv=notrunc if=os.fat12 of=$@
-# splice in zip at the end
- set -x; dd skip=$$(( $(space_before_zip_bytes) )) seek=$$(( $(space_before_zip_bytes) )) bs=1 conv=notrunc if=os.zip.adjusted of=$@
+# pad with zeroes to prepare for GPT table
+ set -x; dd if=/dev/zero seek=$$(( $(gpt_mirror_end) - 1 )) bs=1 count=1 conv=notrunc of=$@
# patch the partition table
printf "p\nd\nn\np\n1\n$$(( $(fat12_start) / $(sector_size) ))\n$$(( $(fat12_size_sectors) ))\nt\n01\na\n1\np\nw\nq\n" | fdisk $@
+# gdisk commands: recovery, make hybrid, add GPT partition #1 to the hybrid MBR, don't put the EFI partition first,
+# partition type=0x01, bootable=Y, don't add extra partitions, print GPT, print MBR, write, proceed, quit.
+ printf "r\nh\n1\nN\n01\nY\nN\np\no\nw\nY\nq\n" | gdisk $@
+# splice in zip at the end
+ set -x; dd skip=$$(( $(space_before_zip_bytes) )) seek=$$(( $(space_before_zip_bytes) )) bs=1 conv=notrunc if=os.zip.adjusted of=$@
chmod a+x-w $@
os.file: $(os_filename) Makefile
@@ -120,17 +132,30 @@ os.fdisk: $(os_filename) Makefile
fdisk -l $< > $@
os.offsets: $(os_filename) os.32k os.iso os.fat12 os.zip Makefile
- printf 'total_size = 0x%08x\n' $$(( $(os_total_size_sectors) * $(sector_size) )) > $@
- printf 'mbr_start = 0x%08x\n' $$(( $(mbr_start) )) >> $@
- printf 'mbr_end = 0x%08x\n' $$(( $(mbr_end) )) >> $@
- printf '32k_start = 0x%08x\n' $$(( $(header_32k_start) )) >> $@
- printf '32k_end = 0x%08x\n' $$(( $(header_32k_end) )) >> $@
- printf 'iso_start = 0x%08x\n' $$(( $(iso_start) )) >> $@
- printf 'iso_end = 0x%08x\n' $$(( $(iso_end) )) >> $@
- printf 'fat12_start = 0x%08x\n' $$(( $(fat12_start) )) >> $@
- printf 'fat12_end = 0x%08x\n' $$(( $(fat12_end) )) >> $@
- printf 'zip_start = 0x%08x\n' $$(( $(zip_start) )) >> $@
- printf 'zip_end = 0x%08x\n' $$(( $(zip_end) )) >> $@
+ printf 'total_size = 0x%08x\n' $$(( $(os_total_size_sectors) * $(sector_size) )) > $@
+ printf 'mbr_start = 0x%08x\n' $$(( $(mbr_start) )) >> $@
+ printf 'mbr_end = 0x%08x\n' $$(( $(mbr_end) )) >> $@
+ printf '32k_start = 0x%08x\n' $$(( $(header_32k_start) )) >> $@
+ printf '32k_end = 0x%08x\n' $$(( $(header_32k_end) )) >> $@
+ printf 'iso_start = 0x%08x\n' $$(( $(iso_start) )) >> $@
+ printf 'iso_end = 0x%08x\n' $$(( $(iso_end) )) >> $@
+ printf 'fat12_start = 0x%08x\n' $$(( $(fat12_start) )) >> $@
+ printf 'fat12_end = 0x%08x\n' $$(( $(fat12_end) )) >> $@
+ printf 'gpt_mirror_start = 0x%08x\n' $$(( $(gpt_mirror_start) )) >> $@
+ printf 'gpt_mirror_end = 0x%08x\n' $$(( $(gpt_mirror_end) )) >> $@
+ printf 'zip_start = 0x%08x\n' $$(( $(zip_start) )) >> $@
+ printf 'zip_end = 0x%08x\n' $$(( $(zip_end) )) >> $@
+
+# TODO: make each offset a separate file, dependencies will be simpler.
+build/offsets/fat12_start.hex: os.zip os.iso build/offsets Makefile
+ printf '0x%08x' $$(( $(fat12_start) )) > $@
+
+build/offsets/%.dec: build/offsets/%.hex
+ printf '%d' $$(cat $<) > $@
+
+os.hex_with_offsets: $(os_filename) os.offsets
+ hexdump -C $< \
+ | grep -E -e "($$(cat os.offsets | cut -d '=' -f 2 | sed -r -e 's/^\s*0x(.*).$$/^\10/' | tr '\n' '|')^)" --color=yes > $@
os.ndisasm.disasm: $(os_filename) Makefile ../utils/compact-ndisasm.sh
../utils/compact-ndisasm.sh $< $@
@@ -139,13 +164,15 @@ os.reasm.asm: os.ndisasm.disasm Makefile
sed -r -e 's/^[^ ]+ +[^ ]+ +//' $< > $@
os.reasm: os.reasm.asm $(os_filename) Makefile
- nasm $< -o $@
- @echo "diff $@ $(os_filename)"
- @diff $@ $(os_filename) \
- && echo "[1;32mRe-assembled file is identical to $(os_filename)[m" \
- || (../utils/compact-ndisasm.sh $@ os.reasm.disasm; \
- echo "[0;33mRe-assembled file is different from $(os_filename). Use meld os.ndisasm.disasm os.reasm.disasm to see differences.[m"; \
- exit 0) # For now ignore this error, since we cannot have a reliable re-assembly of arbitrary data.
+# For now ignore this test, since we cannot have a reliable re-assembly of arbitrary data.
+ true
+# nasm $< -o $@
+# @echo "diff $@ $(os_filename)"
+# @diff $@ $(os_filename) \
+# && echo "[1;32mRe-assembled file is identical to $(os_filename)[m" \
+# || (../utils/compact-ndisasm.sh $@ os.reasm.disasm; \
+# echo "[0;33mRe-assembled file is different from $(os_filename). Use meld os.ndisasm.disasm os.reasm.disasm to see differences.[m"; \
+# exit 0)
#os.arm.disasm: $(os_filename) Makefile
# arm-none-eabi-objdump --endian=little -marm -b binary -D --adjust-vma=0x8000 $< > $@
@@ -159,14 +186,14 @@ clean: Makefile
for f in $(built_files); do echo "/$$f"; done > $@
.PHONY: test
-test: $(tests) test/noemu all Makefile
+test: $(tests_emu) $(tests_noemu) $(tests_requiring_sudo) all Makefile
-.PHONY: $(tests)
-$(tests): $(os_filename) ../deploy-screenshots Makefile
+.PHONY: $(tests_emu)
+$(tests_emu): $(os_filename) ../deploy-screenshots Makefile
cd .. && ./utils/gui-wrapper.sh 800x600x24 ./$@.sh example-os/$<
.PHONY: test/noemu
-test/noemu: test/zip os.reasm test/sizes test/fat12_contents Makefile
+test/noemu: $(tests_noemu) Makefile
.PHONY: test/zip
test/zip: $(os_filename) Makefile
@@ -180,3 +207,21 @@ test/sizes: os.32k $(os_filename) Makefile
# check that the fat filesystem has the correct contents
test/fat12_contents: $(os_filename)
mdir -i "$<@@$$(( $(fat12_start) ))" :: | grep -E "^os\s+zip\s+"
+
+.PHONY: test/requiring_sudo
+test/requiring_sudo: $(tests_requiring_sudo) Makefile
+
+# check that the fat filesystem can be mounted and has the correct contents
+.PHONY: test/fat12_mount
+test/fat12_mount: $(os_filename) build/mnt_fat12 build/offsets/fat12_start.dec Makefile
+ sudo umount build/mnt_fat12 || true
+ sudo mount -o loop,ro,offset=$$(cat build/offsets/fat12_start.dec) $< build/mnt_fat12
+ ls -l build/mnt_fat12 | grep os.zip
+ sudo umount build/mnt_fat12
+
+.PHONY: test/iso_mount
+test/iso_mount: $(os_filename) build/mnt_iso Makefile
+ sudo umount build/mnt_iso || true
+ sudo mount -o loop,ro $< build/mnt_iso
+ ls -l build/mnt_iso | grep os.zip
+ sudo umount build/mnt_iso
diff --git a/example-os/os.asm b/example-os/os.asm
@@ -63,6 +63,9 @@ db 0x55, 0xaa ;; 0x1fe End the bootsector with 55 AA, which is the MBR signatur
;;; This is the end of the first 512 bytes (the bootsector).
+;;; Leave some space for the GPT header and partition table entries (LBA0 = MBR, LBA1 = header, LBA2..33 = GPT partition tables)
+times (34*512)-($-$$) db 0
+
;;; After the bootsector, close the sh here-document skipped via : <<'EOF'
db `\n`
db `EOF\n`
@@ -82,5 +85,5 @@ db `exit\n`
db `:loop\n`
db `GOTO loop\n`
-;;; Fill up to 32k with 0. This constitutes the first 32k of the ISO image.
+;;; Fill up to 32k with 0. This constitutes the reserved first 32k at the beginning of an ISO9660 image.
times (32*1024)-($-$$) db 0
