82 lines
3.5 KiB
Plaintext
82 lines
3.5 KiB
Plaintext
This directory contains patches for the OKL4 kernel version 2.1.1-patch.9.
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:'syscall_pic.patch':
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The original distribution of the OKL4 kernel comes with x86 syscall bindings
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that use absolute addressing modes. Therefore, code using L4 syscalls
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cannot be compiled as position-independent code (gcc option '-fPIC').
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Unfortunately, shared libraries must be compiled as position independent
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because the location of such a library's text segment is not known at
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compile time. Consequently, L4 syscalls cannot be issued by shared
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libraries, which is a severe limitation. The patch fixes the problem
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by changing all L4 syscall bindings by removing PIC-incompatible
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addressing modes. It does not affect the functionality of the kernel.
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:'eabi_build.patch':
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The build system of the orignal OKL4 distribution is not prepared to
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compile ARM EABI binaries as generated by modern tool chains such as the
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Codesourcery GCC. The patch applies the needed changes to the OKL4 build
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infrastructure.
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:'reply_tid.patch':
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The original OKL4 kernel does not report the global thread ID of the
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sender to the receiver of an IPC. Instead, the so called "threadhandle"
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of the sender thread is provided. This value is the KTCB index of the
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thread. It can be used as IPC destination when sending the reply but
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is otherwise meaningless to the userland. However, this becomes a
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problem when handing page faults because the page-fault handler is not
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able to identify the faulting thread - only the faulting space. There
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is no way for the pager to lookup the thread context of the faulting
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thread with the information of the page-fault message. The patch changes
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OKL4 such that the global thread ID of the sender is provided to the
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receiver.
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:'kdb_reboot.patch':
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This patch enables machine reboot from the kernel debugger.
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:'char_bit.patch':
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This patch resolves the conflict of definitions of 'CHAR_BIT' between
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libc and the OKL4 headers. 'CHAR_BIT' is normally defined by the libc
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('limits.h') but it also appears in OKL4's 'types.h'. The patch relaxes
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the conflict by making 'CHAR_BIT' an enum value rather then a '#define'.
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This way, OKL4's headers included into a dedicated 'Okl4' C++ namespace
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(as done by Genode) will result in a 'Okl4::CHAR_BIT' name, not causing
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trouble with libc headers included by the same compilation unit.
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:'gdt_init.patch':
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This patch fixes a off-by-one bug that prevents OKL4 from running on
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VirtualBox with VT-x disabled. The original kernel calculates the
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last segment address in a wrong way, causing a conflict between
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GDT and TSS. As a result, VirtualBox stops with a 'GURU_MEDITATION'
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error.
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:'invalid_opcode_exception_ipc.patch':
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When an invalid opcode gets executed, OKL4 switches to the kernel debugger
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console instead of sending an exception IPC to the userland. This patch
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fixes the problem by removing the code that invokes the debugger console.
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:'bda.patch':
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This patch reads out the I/O port of the serial device from the BIOS data
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area (on x86).
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Applying the patches
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--------------------
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To apply a patch to the OKL4 kernel, use the 'patch' command. First check
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the directory given at the header of the patch. It may contain a directory
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prefix (such as 'a/'), which does not actually exist. This prefix is usually
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generated by the tool used to create the patch. In this case, use the '-p'
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option of the patch command. To apply the patch with the first part of the
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path stripped, issue the following command (make sure that you changed to
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the base directory of the OKL4 kernel):
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! patch -p1 < /path/to/syscall_pic.patch
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