mirror of
https://github.com/danbulant/Cosmos
synced 2026-05-19 20:39:01 +00:00
97 lines
4.8 KiB
HTML
97 lines
4.8 KiB
HTML
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<title></title>
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</head>
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<body>
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<h3>
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Introduction</h3>
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<p>
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The debugger is a monumental piece of work and one of the key enabling elements
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of making Cosmos unique. We have put an immense amount of work into the debugger
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and will continue to do so even though it takes a lot of time and detracts from
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resources that could be used to develop Cosmos kernel code. We do this because
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we believe that every hour put into the debugger will be returned in many times
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as many hours saved in kernel development. Some users have criticized this
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approach, but we stand firm in this belief and believe that Cosmos success rests
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heavily on the debugger and tight Visual Studio integration.</p>
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<h3>
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Obstacles</h3>
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<p>
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The Visual Studio debugger is only lightly documented (lightly might be a kind
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adjective). There are few if any samples and much of our progress is the result
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of sheer determination and experimentation.</p>
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<h3>
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Debug Stub</h3>
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<h3>
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</h3>
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<h3>
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Communication</h3>
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Communication currently uses the serial port. Other methods such as ethernet are
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planned in the future.<h3>
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Data Files</h3>
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<p>
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All files are generated in the output directory. Usually this is bin/debug or
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bin/release.</p>
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<h4>
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CMAP file</h4>
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The CMAP file maps assembler labels to physical memory locations. These labels
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include data (internal data, static fields, string literals) and code locations
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(method entry, points for each line of code, internal locations for exception
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handling).<br />
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<br />
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The format is address, tab, label. A small excerpt is shown below.<pre>00500000 DebugTraceMode
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00500004 DebugStatus
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00500008 DebugRunning </pre>
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<h4>
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CXDB file</h4>
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<p>
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The CXDB contains a series of records with information about the methods. Each
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record contains:</p>
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<ul>
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<li>LabelName (string) - Label as used in the ASM file to start the method. Each
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label emitted exists, that is many labels for each method.</li>
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<li>Address (uint) - Address in physical memory.</li>
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<li>StackDifference (int) - Size of stack. Arguments only?</li>
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<li>AssemblyFile (string) - .NET assmebly containing IL source.</li>
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<li>TypeToken (int) - .NET token for the containing type.</li>
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<li>MethodToken (int) - .NET token for the method.</li>
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<li>ILOffset (int) - Offset into the .NET assembly file where the method resides.</li>
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<li>MethodName (string) - Name of the method. Not unique, as many labels exist per
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method.</li>
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</ul>
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Cosmos.Debug.Common.CDebugger.SourceInfos is a class for reading the CXDB file
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(and the PDB too). Currently the CXDB is handled by a dataset and saved as an
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XML file. However we never need the whole file in RAM, and in the future it
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should be changed to a database such as embedded Firebird (SQL Express has size
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limits we could forseeably encounter).<h4>
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ASM file</h4>
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<p>
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The ASM file is actually generated by the Cosmos compiler, however in some cases
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it can be useful to the debugger. Most notably to display the assembly during
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interaction with GDB, or the given assembly for .NET code. Currently it is only
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used by the Cosmos GDB client, however there are plans to integrate assembly
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view and GDB debugging into Visual Studio.</p>
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<h4>
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PDB files</h4>
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<p>
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PDB files are debug files generated by the .NET compiler. (<a
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href="http://www.wintellect.com/CS/blogs/jrobbins/archive/2009/05/11/pdb-files-what-every-developer-must-know.aspx">More
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info</a>, although its summed up as "A .NET PDB only contains two pieces of
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information, the source file names and their lines and the local variable names.
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All the other information is already in the .NET metadata so there is no need to
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duplicate the same information in a PDB file. ")</p>
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<p>
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PDB maps methods to source file locations. Given a method name, the source file
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and exact start and end locations can be determined. It also contains
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"SequencePoints" which map to individual source code lines in a source file.</p>
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<h4>
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LOG.html</h4>
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<p>
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If logging is enabled, a log file containting the scan tree used by the Cosmos
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compiler will be generated.</p>
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</body>
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</html>
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