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| -rw-r--r-- | docs/tex/epm.tex | 142 | ||||
| -rw-r--r-- | lib/partition-map.h | 17 |
2 files changed, 152 insertions, 7 deletions
diff --git a/docs/tex/epm.tex b/docs/tex/epm.tex new file mode 100644 index 0000000..f139c2c --- /dev/null +++ b/docs/tex/epm.tex @@ -0,0 +1,142 @@ +\documentclass[12pt]{article} +\usepackage[utf8]{inputenc} +\usepackage[margin=1in]{geometry} +\usepackage{titlesec} +\usepackage{listings} +\usepackage{xcolor} +\usepackage{amsmath} +\usepackage{caption} +\usepackage{longtable} + +\titleformat{\section}{\large\bfseries}{\thesection}{1em}{} +\titleformat{\subsection}{\normalsize\bfseries}{\thesubsection}{1em}{} + +\definecolor{codegray}{gray}{0.95} + +\lstdefinestyle{customc}{ + backgroundcolor=\color{codegray}, + basicstyle=\ttfamily\footnotesize, + keywordstyle=\color{blue}, + commentstyle=\color{gray}, + stringstyle=\color{red}, + breaklines=true, + showstringspaces=false, + frame=single, + language=C +} + +\title{EPM Partition Map Specification} +\author{Amlal EL Mahrouss} +\date{2024-2025} + +\begin{document} + +\maketitle + +\section{Overview} +This document specifies the Explicit Partition Map (EPM) data structures and constants as defined in \texttt{partition\_map.h}. The EPM is designed to store partition information in a platform-independent manner with architecture-specific magic identifiers. + +\section{Constants and Macros} + +\subsection{Magic Strings} +\begin{longtable}{|l|l|} +\hline +\textbf{Macro} & \textbf{Description} \\ +\hline +\texttt{EPM\_MAGIC\_X86} & "EPMAM", used on AMD64 \\ +\texttt{EPM\_MAGIC\_RV} & "EPMRV", used on RISC-V \\ +\texttt{EPM\_MAGIC\_ARM} & "EPMAR", used on ARM \\ +\texttt{EPM\_MAGIC\_64X0} & "EPM64", for custom 64x0 architecture \\ +\texttt{EPM\_MAGIC\_32X0} & "EPM32", for custom 32x0 architecture \\ +\texttt{EPM\_MAGIC\_PPC} & "EPMPC", used on POWER \\ +\texttt{EPM\_MAGIC} & Defaults based on architecture \\ +\hline +\end{longtable} + +\subsection{Layout Macros} +\begin{itemize} + \item \texttt{EPM\_MAX\_BLKS = 128} \\ + Maximum number of blocks in the partition table (first 128 LBAs). + \item \texttt{EPM\_PART\_BLK\_SZ} \\ + Size of the \texttt{part\_block} structure. + \item \texttt{EPM\_PART\_BLK\_START = 0} \\ + Start LBA of EPM partition headers. + \item \texttt{EPM\_REVISION = 2} \\ + Current revision of the EPM format. +\end{itemize} + +\section{Data Structures} + +\subsection{boot\_guid\_t} +\begin{lstlisting}[style=customc] +typedef struct boot_guid { + uint32_t data1; + uint16_t data2; + uint16_t data3; + uint8_t data4[8]; +} __attribute__((packed)) boot_guid_t; +\end{lstlisting} +A GUID structure used for identifying partitions. + +\subsection{part\_block} +\begin{lstlisting}[style=customc] +struct __attribute__((packed)) part_block { + ascii_char_t magic[5]; // Magic string + ascii_char_t name[32]; // Human-readable name + boot_guid_t uuid; // Partition UUID + int32_t version; // Partition version + int32_t num_blocks; // Number of blocks + int64_t lba_start; // Starting LBA + int64_t sector_sz; // Sector size + int64_t lba_end; // Ending LBA + int16_t type; // Partition type + int32_t fs_version; // Filesystem version + ascii_char_t fs[16]; // Filesystem name + ascii_char_t reserved[401]; // Reserved for future use +}; +\end{lstlisting} + +\subsection*{Filesystem Type Values} +\begin{longtable}{|l|l|} +\hline +\textbf{Enum Value} & \textbf{Meaning} \\ +\hline +\texttt{EPM\_INVALID} & \texttt{0x00} - Invalid/undefined \\ +\texttt{EPM\_GENERIC\_OS} & \texttt{0xcf} - Generic OS partition \\ +\texttt{EPM\_LINUX} & \texttt{0x8f} - Linux partition \\ +\texttt{EPM\_BSD} & \texttt{0x9f} - BSD partition \\ +\texttt{EPM\_NEKERNEL\_OS} & \texttt{0x1f} - NeKernel-specific \\ +\hline +\end{longtable} + +\section{Functions} + +\subsection{\texttt{cb\_filesystem\_exists}} +\begin{lstlisting}[style=customc] +boolean cb_filesystem_exists(caddr_t fs, size_t len); +\end{lstlisting} +Checks if a filesystem name is supported. + +\subsection{\texttt{cb\_parse\_partition\_block\_data\_at}} +\begin{lstlisting}[style=customc] +bool cb_parse_partition_block_data_at( + voidptr_t blob, + size_t blob_sz, + size_t index, + size_t* end_lba, + size_t* start_lba, + size_t* sector_sz); +\end{lstlisting} +Parses an EPM partition block from a blob at the specified index and returns LBA information. + +\subsection{\texttt{cb\_parse\_partition\_block\_at}} +\begin{lstlisting}[style=customc] +part_block_t* cb_parse_partition_block_at( + voidptr_t blob, + size_t blob_sz, + size_t index); +\end{lstlisting} +Returns a pointer to a parsed EPM partition block at the specified index. + +\end{document} + diff --git a/lib/partition-map.h b/lib/partition-map.h index 05ff83f..28d480a 100644 --- a/lib/partition-map.h +++ b/lib/partition-map.h @@ -1,6 +1,6 @@ /* ------------------------------------------- - Copyright (C) 2024, Amlal EL Mahrouss, all rights reserved. + Copyright (C) 2024-2025, Amlal EL Mahrouss, all rights reserved. ------------------------------------------- */ @@ -35,8 +35,9 @@ #define EPM_MAGIC "EPMMS" /* mass storage */ #endif -#define EPM_MAX_BLKS (128) /* 1 on UEFI EPM. */ +#define EPM_MAX_BLKS (128) /* 1 on UEFI EPM, because of it would only fit on a sector. */ +/// @brief Size of a partition block (roughly 512 bytes) #define EPM_PART_BLK_SZ sizeof(struct part_block) /// @brief Start of EPM headers. @@ -81,11 +82,11 @@ typedef struct part_block part_block_t; ///! @brief variant enum. ///! use it in the boot block version field. enum { - EPM_INVALID = 0x00, - EPM_GENERIC_OS = 0xcf, - EPM_LINUX = 0x8f, - EPM_BSD = 0x9f, - EPM_ZKAOS = 0x1f, + EPM_INVALID = 0x00, + EPM_GENERIC_OS = 0xcf, + EPM_LINUX = 0x8f, + EPM_BSD = 0x9f, + EPM_NEKERNEL_OS = 0x1f, }; /// @brief check for supported filesystem. @@ -95,6 +96,8 @@ boolean cb_filesystem_exists(caddr_t fs, size_t len); bool cb_parse_partition_block_data_at(voidptr_t blob, size_t blob_sz, size_t index, size_t* end_lba, size_t* start_lba, size_t* sector_sz); +/// @brief Parse Partition block info at index. +/// @param index the partition block to parse. part_block_t* cb_parse_partition_block_at(voidptr_t blob, size_t blob_sz, size_t index); #endif // ifndef __PARTITION_MAP_H__ |