write about the support tools

Author: asdfugil

tools/README.md

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+# Support Tools
+
+This directory contain support tools for HoolockLinux.
+They are intended to be ran under jailbroken iOS/tvOS/bridgeOS, or a SSH ramdisk.
+
+Download precompiled tools: [iOS/iPadOS](https://nightly.link/hoolocklinux/docs/workflows/build/master/hoolock-support-iphoneos.zip) | [tvOS](https://nightly.link/hoolocklinux/docs/workflows/build/master/hoolock-support-appletvos.zip) | [bridgeOS](https://nightly.link/hoolocklinux/docs/workflows/build/master/hoolock-support-bridgeOS.zip)
+
+## Disk partition tools
+
+> [!WARNING]
+> These tools could potentially destroy all data on the main disk, so double check.
+
+### gdisk
+
+This is the usual gpt partitioning tool found on many unixes.
+
+It is used to inspect and modify the partition table.
+
+It should be signed with entitlements in `gdisk.xml`.
+
+### resize.c / resize_apfs
+
+This is an apfs container resize tool.
+
+It should be signed with entitlements in `resize.xml`.
+
+Usage: `./resize_apfs <container BSD name> <size in bytes>`
+
+Resize the container to N bytes, such as 21474836480 in the following example.
+There are alignment restrictions so pick a 1048576-byte aligned size.
+
+```
+./resize_apfs disk0s1 21474836480
+```
+
+It is also possible to resize the container to the max size:
+
+> [!CAUTION]
+> On iOS 13 and below this might ignore the gpt and resize the apfs to max which would break the filesystem. Recommend specifying the exact partition size instead.
+
+```
+./resize_apfs disk0s1 0
+```
+
+During an online resize, all file system operations will be frozen, so in normal iOS the device will become unresponsive
+
+After resizing, the gpt can be modified with gdisk.
+
+
+### Caveats
+
+On iOS 11-13 the default snapshot makes the container unresizable.
+One can delete and recreate the snapshot with a tool like [`snaputil`](https://github.com/ahl/apfs) from ramdisk and resizing should work.
+
+In order for a resize to work, the SEP firmware must be loaded, and gigalocker
+must be initialized. This is already done in normal iOS. In a ramdisk, this can
+also be done on iOS/iPadOS 15 and below.
+(Might also be possible on higher tvOS/bridgeOS versions)
+
+If you use [SSHRD_Script](https://github.com/verygenericname/SSHRD_Script.git), the following command should do:
+
+```
+mount_filesystems
+```
+
+In a ramdisk, you might need somewhere writable to put the tools. On iOS 14 and above this is simple:
+
+```
+mount_tmpfs /mnt5
+```
+
+On iOS 13 and below, tmpfs is not supported, so a ramdisk needs to be created and formatted:
+
+```
+disk=$(hdik ram://16384) # 16384 KiB
+newfs_hfs $disk
+mount_hfs $disk /mnt5
+```