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@ -133,7 +133,7 @@ OpenWrt target. |
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\subsubsection{Pluging a serial port} |
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By using a serial port, you may reach the console that is being shown by the device |
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By using a serial port and a level shifter, you may reach the console that is being shown by the device |
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for debugging or flashing purposes. By analysing the output of this device, you can |
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easily notice if the device uses a Linux kenrel or something different. |
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@ -188,11 +188,11 @@ You should anyway be able to use the following components: |
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\item binary tools to create a valid firmware image |
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\end{itemize} |
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Your work is now divided into the following tasks: |
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Your work can be divided into the following tasks: |
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\begin{itemize} |
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\item create a clean patch of the hardware specific part of the linux kernel |
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\item spot potential kernel GPL violations especially on firewall and USB stack stuff |
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\item spot potential kernel GPL violations especially on netfilter and USB stack stuff |
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\item make the binary drivers work, until there are open source drivers |
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\item use standard a GNU toolchain to make working executables |
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\item understand and write open source tools to generate a valid firmware image |
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@ -243,12 +243,12 @@ initialized at startup, as well as processor detection and other boot time |
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specific fixes. |
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The second patch will contain all useful definitions for that board: adresses, |
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kernel granularity, redifinitions, processor family and features ... |
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kernel granularity, redefinitions, processor family and features ... |
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The third patch may contain drivers for: serial console, ethernet NIC, wireless |
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NIC, USB NIC ... Most of the time this patch contains nothing else than "glue" |
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code that has been added to make the binary driver work with the Linux kernel. |
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This code might not be useful if you plan on writing from scratch drivers for |
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This code might not be useful if you plan on writing drivers from scratch for |
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this hardware. |
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\subsubsection{Using the device bootloader} |
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@ -258,13 +258,13 @@ been powered on. This program, can be more or less sophisticated, some do let yo |
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do network booting, USB mass storage booting ... The bootloader is device and |
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architeture specific, some bootloaders were designed to be universal such as |
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RedBoot or U-Boot so that you can meet those loaders on totally different |
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platforms and expect to work the same way. |
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platforms and expect them to behave the same way. |
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If your device runs a proprietary operating system, you are very likely to deal |
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with a proprietary boot loader as well. This may not always be a limitation, |
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some proprietary bootloaders can even have source code available (i.e : Broadcom CFE). |
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According to the bootloader features, hacking on th device will be more or less |
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According to the bootloader features, hacking on the device will be more or less |
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easier. It is very probable that the bootloader, even exotic and rare, has a |
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documentation somewhere over the Internet. In order to know what will be possible |
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with your bootloader and the way you are going to hack the device, look over the |
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@ -311,7 +311,6 @@ order to make binary drivers work with your custom kernel: |
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\item CONFIG\_DEBUG\_KERNEL |
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\item CONFIG\_DETECT\_SOFTLOCKUP |
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\item CONFIG\_DEBUG\_KOBJECT |
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\item CONFIG\_EMBEDDED |
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\item CONFIG\_KALLSYMS |
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\item CONFIG\_KALLSYMS\_ALL |
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\end{itemize} |
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@ -337,8 +336,8 @@ A firmare format is most of the time composed of the following fields: |
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\begin{itemize} |
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\item header, containing a firmare version and additional fields: Vendor, Hardware version ... |
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\item CRC32 checksum on either the whole file or just part of it |
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\item Binary or compressed kernel image |
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\item Binary or compressed root filesystem image |
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\item Binary and/or compressed kernel image |
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\item Binary and/or compressed root filesystem image |
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\item potential garbage |
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\end{itemize} |
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