pbemu
User-mode emulation for PocketBook 6.1-6.11 firmware on Linux desktop (podman + Wayland)
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pbemu src informer
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src
CMakeLists.txt
README.md
README.md

informer — ARM-side viewer companion service #

informer is a small ARM guest process launched by pbemu start through PocketBook's monitor service manager. Its job is to publish exactly the metadata the host viewer needs, using official firmware APIs only.

Build #

# From repo root (builds inside the pbdev container):
./pbemu build [firmware]

Output: src/informer/build-arm/informer

Like the shim, informer links against the staged firmware's own ARM libraries (libinkview.so, libhwconfig.so, and rootfs/lib/libc.so.6), so ./pbemu install <firmware.zip> must be run first.

Runtime #

pbemu start stages the built binary into the live firmware tree as /ebrmain/bin/informer, then launches it directly via qemu-arm inside the container before starting the host viewer.

Relevant environment variables:

Variable Default Purpose
PB_SYSTEM_INFORMER_BIN src/informer/build-arm/informer Override the ARM informer binary used at startup
PB_INFORMER_POLL_MS 100 Snapshot poll interval in milliseconds
PB_DEVICE_STAGE_ROOT set by pbemu start Live stage root used for logging and runtime files

Logs are written to $PB_DEVICE_STAGE_ROOT/var/log/informer.log.

Published protocol #

src/common/pb_informer.h defines pb_informer_state, a fixed-layout snapshot shared between ARM32 and x86-64.

Key fields:

Field group Meaning
magic, version, struct_size Protocol validation
sequence Odd/even seqlock counter for lock-free snapshot reads
flags Validity bits for task ids, framebuffer info, touch matrix, and names
active_task_id, active_subtask_id Current foreground task/subtask from GetActiveTask()
fbshmkey, fbshmsize Active task framebuffer SHM id/size
width, height, depth, stride Normalised framebuffer geometry
pixel_data_offset, fb_y_offset Pixel-data start offset and wrapped-framebuffer Y origin
touch_matrix[8] Touch-panel affine transform
task_name, subtask_name Human-facing window-title strings

Writer protocol:

  1. Increment sequence to an odd value.
  2. Copy the new snapshot payload.
  3. Increment sequence to the next even value.

Readers accept a snapshot only when both reads of sequence match and are even.

Source map #

src/informer_sdk.h — minimal firmware SDK declarations #

Declares the subset of PocketBook APIs and structs the service needs:

  • InitInkview(), SignalTaskStarted()
  • GetActiveTask(), GetTaskInfo(), GetTaskFramebufferInfo()
  • TaskNameToHumanName()
  • init_hwconfig(), device_touchpanel_getmatrix()
  • taskinfo, subtaskinfo, and task-flag constants

src/main.c — service entry point and publisher loop #

Owns the entire runtime for the service.

Key functions:

  • open_state_segment() — creates/attaches the SysV SHM segment at PB_INFORMER_SHM_KEY
  • fill_touch_matrix() — copies the hwconfig touch matrix when available
  • fill_task_names() — derives task/subtask labels from PocketBook task metadata
  • fill_framebuffer_info() — normalises iv_fbinfo into viewer-friendly geometry fields
  • fill_snapshot() — assembles one full pb_informer_state
  • publish_snapshot() — writes the snapshot using the odd/even sequence protocol

main() installs signal handlers, opens the log file, initialises InkView, self-registers with the firmware task manager, optionally initialises hwconfig, and then republishes snapshots until shutdown.

Design notes #

  • Uses official firmware APIs only; no monitor SHM offset scraping.
  • Publishes framebuffer geometry on the ARM side so the viewer does not need to decode guest headers to discover layout.