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\documentclass{article}
\usepackage{graphicx} % Required for inserting images
\title{The PCI Tree System}
\author{Amlal El Mahrouss}
\date{\today}
\usepackage{listings}
\lstset { %
language=C++,
}
\begin{document}
\maketitle
\section{Abstract}
The PCI tree is an architecture designed to abstract away device specific data. One leaf might for instance hold an AHCI's HBA (Host Bus Adapter) into a '/pci-tree/@ahci' for instance. The advantage of this approach is the ability to quickly lookup and recognize a device from a tree given by a firmware at handoff.
\section{The Protocol}
Each leaf has a identification number of '0xfeedd00d', then followed by the version in a binary encoded format (0x1000). The offset and size of the offset and then given by the firmware. A PCI-Tree is assembled by the firmware itself. As the structures are not packed, thus multi-platform portability isn't possible.
\section{Trade-offs}
The trade-offs (portability, complexity) are largely justified by the need of a better and more straightforward way to recognize devices at the firmware level, the PCI tree approach helps us do exactly that.
\subsection{Implementation of a PCI-Tree Leaf}
Language of implementation is the C programming language
\begin{lstlisting}
struct hw_cb_pci_tree {
cb_pci_num_t d_magic;
cb_pci_num_t d_version;
cb_pci_num_t d_off_props;
cb_pci_num_t d_off_struct;
cb_pci_num_t d_sz_props;
cb_pci_num_t d_sz_struct;
cb_pci_num_t d_first_node;
cb_pci_num_t d_next_sibling;
cb_pci_char_t d_name[NB_PCI_NAME_LEN];
};
\end{lstlisting}
\section{Official Implementations}
\subsection{ISO C}
\begin{ImplC}
\item {SNU Trusted Base:} \url(https://snu.systems)
\item {NeBoot (NeKernel Boot):} \url(https://github.com/nekernel-org/neboot)
\end{ImplC}
\subsection{ISO C++}
\begin{ImplCxx}
\item {No Implementation yet}
\end{ImplCxx}
\subsection{Forth}
\begin{ImplForth}
\item {No Implementation yet}
\end{ImplForth}
\end{document}
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