a5061ecec5
An effort was started some time ago to consolidate all internal documentation in the git tree. However, this was just an accumulation of files in various formats without any strucutre or way to browse it, which results in no one even knowing that we have docs here. This converts most of the files to restructuredtext and uses Sphinx to generate an HTML browsable user manual (with a table of content and a first attempt to put things in a global hierarchy). There are almost no changes to the documentation content in this commit (some obviously obsolete things were removed). The plan is to get the toolchain up and running to make these docs easily available, and only then see about improving the content. We can migrate some things off the wiki and website, and rework the table of contents to have some more hierarchy levels because currently it's a bit messy. Change-Id: I924ac9dc6e753887ab56f18a09bdb0a1e1793bfd Reviewed-on: https://review.haiku-os.org/c/haiku/+/4370 Reviewed-by: Niels Sascha Reedijk <niels.reedijk@gmail.com>
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69 lines
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Using PCI serial ports for debugging
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====================================
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Modern systems usually don't come with a built-in serial port anymore. This
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is unconvenient for low level debugging, since the serial port allows access
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to early boot log as well as kernel debugger, even when the display or keyboard
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are not working.
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It is fortunately possible to add a serial port over the PCI bus on machines
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which have appropriate expansion ports. This can be done using expresscard,
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mini-PCI, or PCI express ports.
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Devices known to work
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---------------------
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Dexlan XMT01A (https://www.accessoires-informatiques.com/Prix/EXPRESSCARD-PCIE-POUR-PORTABLE-23842.html)
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Uses MOSCHIP 9922 controller
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Devices to be tested
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--------------------
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https://smile.amazon.com/Industrial-Desktop-Bracket-Moschip-MCS9922/dp/B003D3MFHM/
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Configuring
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-----------
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- Install the card in your computer
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- Boot Haiku and look in the syslog for the PCI bus scan for the device:
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.. code-block:: text
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KERN: PCI: [dom 0, bus 5] bus 5, device 0, function 0: vendor 9710, device 9922, revision 00
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KERN: PCI: class_base 07, class_function 00, class_api 02
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KERN: PCI: vendor 9710: MosChip Semiconductor Technology Ltd.
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KERN: PCI: device 9922: MCS9922 PCIe Multi-I/O Controller
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KERN: PCI: info: Communication controller (Serial controller, 16550)
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KERN: PCI: line_size 10, latency 00, header_type 80, BIST 00
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KERN: PCI: ROM base host 00000000, pci 00000000, size 00000000
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KERN: PCI: cardbus_CIS 00000000, subsystem_id 1000, subsystem_vendor_id a000
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KERN: PCI: interrupt_line 0b, interrupt_pin 01, min_grant 00, max_latency 00
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KERN: PCI: base reg 0: host 00004000, pci 0000KERN: 4000, size 00000008, flags 01
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KERN: PCI: base reg 1: host f1c01000, pci f1c01000, size 00001000, flags 00
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KERN: PCI: base reg 2: host 00000000, pci 00000000, size 00000000, flags 00
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KERN: PCI: base reg 3: host 00000000, pci 00000000, size 00000000, flags 00
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KERN: PCI: base reg 4: host 00000000, pci 00000000, size 00000000, flags 00
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KERN: PCI: base reg 5: host f1c00000, pci f1c00000, size 00001000, flags 00
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KERN: PCI: Capabilities: MSI, PM, PCIe
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KERN: PCI: Extended capabilities: Virtual Channel, Advanced Error Reporting
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Write down the address of "base reg 0", this is where the serial port registers
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are mapped (it is probably possible to get this information from lspci on Linux
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as well?)
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Configure serial debug in config/settings/kernel/drivers/kernel:
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.. code-block:: text
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serial_debug_output true
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serial_debug_speed 115200
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serial_debug_port 0x4000
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Now your kernel is configured to send its output to the serial port. You can
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connect another machine to it (using an USB to serial adapter and a NULL modem
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cable, for example) and use SerialConnect or a similar tool to see the output
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and access the KDL prompt.
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Happy debugging!
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