Embedded Linux Project (sibyl)

Building

Kernel Module

cd kernel
make
sudo make install

Userspace

mkdir build && cd build
cmake ..
make

The binaries will be in:

• build/daemon/daemon

• build/clients/*

Communication

Userspace

The client programs that aggregate the desired system data may send them to the daemon process. This is done via a simple packet, daemon_measurement_t which is defined in common/include/protocol.h:

#define MAX_DAEMON_PACKET_SIZE PIPE_BUF
#define DAEMON_PACKET_HEADER_SIZE sizeof(uint8_t) + sizeof(uint16_t)
#define MAX_DAEMON_PACKET_DATA_SIZE MAX_DAEMON_PACKET_SIZE - DAEMON_PACKET_HEADER_SIZE

typedef struct {
    uint8_t measurement_id;
    uint16_t size;
    uint8_t data[MAX_DAEMON_PACKET_DATA_SIZE];
} daemon_measurement_t;

The packet size equals to the size of PIPE_BUF (4096). The communication to the deamon is implemented via a named pipe, the size ensure that the packet is atomic, i.e. it is written to the pipe in one go.

• The first byte contains the measurement id, so the maximum number of different measurements client is 255.
• The second and third bytes contain the size of the data in the packet.
• All following bytes contain the data.