Add reMarkable Paper Pure (Tatsu) support

Cargo.toml

@@ -4,8 +4,13 @@ version = "1.5.0"
 authors = ["Rien Maertens <rien.maertens@posteo.be>"]
 edition = "2024"
 
+[features]
+default = []
+# Pen cursor overlay — requires libremarkable (armhf/rM2 only, not aarch64/Tatsu)
+cursor = ["libremarkable"]
+
 [dependencies]
 anyhow = "1.0"
 lz-fear = "0.2"
 clap = { version = "4.5", features = [ "derive" ] }
-libremarkable = { version = "0.7", features = [ "input" ], default-features = false }
+libremarkable = { version = "0.7", features = [ "input" ], default-features = false, optional = true }

README.md

@@ -4,6 +4,7 @@ reMarkable screen sharing over SSH.
 
 [![rm1](https://img.shields.io/badge/rM1-supported-green)](https://remarkable.com/store/remarkable)
 [![rm2](https://img.shields.io/badge/rM2-supported-green)](https://remarkable.com/store/remarkable-2)
+[![rmpaperpure](https://img.shields.io/badge/rM_Paper_Pure-supported-green)](docs/tatsu.md)
 
 ![A demo of reStream](extra/demo.gif)
 
@@ -90,6 +91,8 @@ $ scp restream.arm.static root@10.11.99.1:/home/root/restream
 $ ssh root@10.11.99.1 'chmod +x /home/root/restream'
 ```
 
+> **Note for reMarkable Paper Pure users:** the Paper Pure uses an aarch64 processor and requires a separate binary. See [docs/tatsu.md](docs/tatsu.md) for build instructions.
+
 ## Usage
 
 1. Connect your reMarkable with the USB cable.
@@ -179,6 +182,8 @@ If you want to play with the `restream` code, you will have to [install Rust](ht
 
 There are three ways of building the required restream binary for streaming the reMarkable framebuffer. For these approaches, the generated restream binary will be located under `target/armv7-unknown-linux-gnueabihf/release/restream`.
 
+> **reMarkable Paper Pure:** requires an aarch64 binary instead. See [docs/tatsu.md](docs/tatsu.md).
+
 - **Using nix flakes**
   With [Nix](https://nixos.org/guides/install-nix.html) installed you can
   create the development environment with `nix-shell` or (when using

docs/tatsu.md

@@ -0,0 +1,112 @@
+# reMarkable Paper Pure (Tatsu) Support
+
+## Device Overview
+
+| Property | Value |
+|---|---|
+| Product name | reMarkable Paper Pure |
+| Internal codename | Tatsu |
+| SoC | NXP i.MX 93 (aarch64, ARM Cortex-A55) |
+| Kernel machine string | `reMarkable Tatsu` |
+| OS version location | `/etc/os-release` → `IMG_VERSION` |
+| Confirmed working on | firmware 3.28.0.172 |
+
+## Display Hardware
+
+| Property | Value |
+|---|---|
+| Panel | E Ink Carta™ 1300 |
+| Physical resolution | 1872 × 1404 (landscape) |
+| DRM driver | `eink-carta-panel` |
+| DRM mode | 260×1408 (waveform output, not pixels) |
+
+The display is driven via DRM/KMS through `/dev/dri/card0`. The DRM mode
+(260×1408) is the packed E Ink waveform output size, not the pixel resolution.
+
+## How It Works
+
+xochitl renders the UI into a **BGRA color buffer** in its own heap memory. This
+is the same buffer its built-in screen share feature reads from. reStream reads
+directly from this buffer via `/proc/<pid>/mem`.
+
+### Finding the buffer
+
+The buffer is located by scanning `/proc/<xochitl_pid>/maps` for the first
+anonymous `rw-p` mapping of 10–16 MB that appears immediately after the last
+`/dev/dri/card0` entry. This is reliable across restarts as long as the firmware
+version does not change.
+
+### Buffer layout
+
+The buffer stores the display content in **portrait orientation** (1404×1872),
+regardless of how the device is held. The landscape content is rotated 90° CCW
+into the portrait frame by xochitl.
+
+| Property | Value |
+|---|---|
+| Pixel format | BGRA (4 bytes/pixel) |
+| Frame dimensions | 1404 × 1872 pixels |
+| Stride | 1404 × 4 = 5616 bytes/row |
+| Frame size | 1404 × 1872 × 4 = 10,513,152 bytes |
+
+### Skip offset
+
+The buffer contains a transparent (alpha=0) region before the visible content.
+The skip offset is deliberately **non-row-aligned** so that reading wraps a fixed
+number of columns into the next row, achieving a circular horizontal shift that
+aligns the left edge of the canvas with the start of the output frame. This is
+the same technique used for rM2.
+
+```
+skip = 468 blank rows × 5616 bytes/row + 340 transparent columns × 4 bytes
+     = 2,628,288 + 1,360
+     = 2,629,648 bytes
+```
+
+The 340-column offset was confirmed by dumping the first row of content and
+finding the first opaque pixel (`00 00 00 ff`) at byte offset 1360.
+
+## reStream.sh Parameters
+
+```sh
+"reMarkable Tatsu")
+    width=1404
+    height=1872
+    bytes_per_pixel=4
+    fb_file=":mem:"
+    pixel_format="bgra"
+    skip_offset=2629648
+    dark_mode=false
+    if $landscape; then
+        extra_video_filters="transpose=2"
+    fi
+    landscape=false
+    ;;
+```
+
+`transpose=2` (90° CCW) rotates the portrait buffer back to landscape.
+Use `-p` to stream in portrait orientation without any rotation.
+
+Note: `transpose=1` (the rM2 default via `landscape=true`) produces an
+upside-down result on Tatsu — use `transpose=2` instead.
+
+## Building
+
+The binary must be built for `aarch64` (the Tatsu has no 32-bit compatibility):
+
+```sh
+cross build --release --target=aarch64-unknown-linux-musl
+scp target/aarch64-unknown-linux-musl/release/restream root@10.11.99.1:~/restream
+```
+
+The `--features cursor` build flag is **not supported** on Tatsu — it requires
+`libremarkable` which is armhf-only.
+
+## DRM PRIME (investigated, not viable)
+
+DRM PRIME is a mechanism for sharing GPU memory buffers between processes via
+file descriptors. On Tatsu, xochitl holds 17 GEM buffer handles for the E Ink
+waveform pipeline. We investigated exporting these via `pidfd_getfd()` +
+`DRM_IOCTL_PRIME_HANDLE_TO_FD`, but all 17 buffers contain E Ink waveform data
+(electrical pulse sequences for the panel), not pixel data. The pixel data lives
+in an anonymous heap mapping which PRIME cannot export.

reStream.sh

@@ -131,7 +131,11 @@ ssh_cmd() {
 }
 
 is_current_rm_firmware_version_ge() {
-    current_rm_firmware_version=$(ssh_cmd "grep 'REMARKABLE_RELEASE_VERSION=' /usr/share/remarkable/update.conf | cut -d '=' -f2")
+    # Try update.conf (rM1/rM2), fall back to /etc/os-release IMG_VERSION (Tatsu/newer)
+    current_rm_firmware_version=$(ssh_cmd "grep 'REMARKABLE_RELEASE_VERSION=' /usr/share/remarkable/update.conf 2>/dev/null | cut -d '=' -f2")
+    if [ -z "$current_rm_firmware_version" ]; then
+        current_rm_firmware_version=$(ssh_cmd "grep 'IMG_VERSION=' /etc/os-release 2>/dev/null | cut -d '=' -f2 | tr -d '\"'")
+    fi
     test "$(printf '%s\n' "$current_rm_firmware_version" "$1" | sort -rV | head -n 1)" = "$current_rm_firmware_version"
 }
 
@@ -169,6 +173,21 @@ case "$rm_version" in
 
         skip_offset=8
         ;;
+    "reMarkable Tatsu")
+        width=1404
+        height=1872
+        bytes_per_pixel=4
+        fb_file=":mem:"
+        pixel_format="bgra"
+        skip_offset=2629648
+        dark_mode=false
+        # The buffer is portrait (1404×1872). For landscape view (default),
+        # rotate 90° CCW. For portrait (-p), show as-is.
+        if $landscape; then
+            extra_video_filters="transpose=2"
+        fi
+        landscape=false
+        ;;
     "reMarkable 2.0")
         if ssh_cmd "[ -f /dev/shm/swtfb.01 ]"; then
             width=1404
@@ -313,6 +332,7 @@ set -e # stop if an error occurs
 
 restream_options="-h $height -w $width -b $bytes_per_pixel -f $fb_file -s $skip_offset"
 
+
 if "$cursor"; then
     restream_options="$restream_options -c"
 fi