In order to write PCI ethernet driver. How to implement MMAP in the PCI Ethernet driver

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The final section covers direct memory access (DMA) I/O operations, which provide peripherals with direct access to system memory.,The virtual memory area into which the page range is being mapped.,The beginning and ending virtual addresses for this memory area.,Program DMA information in the DMA controller. addr is a bus address.

# cat / proc / 1 / maps
look at init
08048000 - 0804e000 r - xp 00000000 03: 01 64652 / sbin / init text
0804e000 - 0804 f000 rw - p 00006000 03: 01 64652 / sbin / init data
0804 f000 - 08053000 rwxp 00000000 00: 00 0 zero - mapped BSS
40000000 - 40015000 r - xp 00000000 03: 01 96278 / lib / ld - 2.3 .2.so text
40015000 - 40016000 rw - p 00014000 03: 01 96278 / lib / ld - 2.3 .2.so data
40016000 - 40017000 rw - p 00000000 00: 00 0 BSS
for ld.so
42000000 - 4212e000 r - xp 00000000 03: 01 80290 / lib / tls / libc - 2.3 .2.so text
4212e000 - 42131000 rw - p 0012e000 03: 01 80290 / lib / tls / libc - 2.3 .2.so data
42131000 - 42133000 rw - p 00000000 00: 00 0 BSS
for libc
bffff000 - c0000000 rwxp 00000000 00: 00 0 Stack segment
ffffe000 - fffff000-- - p 00000000 00: 00 0 vsyscall page

# rsh wolf cat / proc / self / maps # # # # x86 - 64(trimmed)
00400000 - 00405000 r - xp 00000000 03: 01 1596291 / bin / cat text
00504000 - 00505000 rw - p 00004000 03: 01 1596291 / bin / cat data
00505000 - 00526000 rwxp 00505000 00: 00 0 bss
3252200000 - 3252214000 r - xp 00000000 03: 01 1237890 / lib64 / ld - 2.3 .3.so
3252300000 - 3252301000 r--p 00100000 03: 01 1237890 / lib64 / ld - 2.3 .3.so
3252301000 - 3252302000 rw - p 00101000 03: 01 1237890 / lib64 / ld - 2.3 .3.so
7 fbfffe000 - 7 fc0000000 rw - p 7 fbfffe000 00: 00 0 stack
ffffffffff600000 - ffffffffffe00000-- - p 00000000 00: 00 0 vsyscall
               start - end perm offset major: minor inode image
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I´ve given only this info to configure a network interface : "port 1 PCI 4", I´ve been searching for any kind of relationship in the system which allow me to find the etc that must be configured...,My question is, which of these are PCI 4 port 1? ,From the Consistent Network Device Naming in Linux paper:

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You can force a device to use a certain device using bind. If the device is already owned by a different driver, you first have to unbind it., Please help me understand the fundamentals behind this P-Channel / driver circuit , Did the universe need the presence of matter and radiation to start expanding? ,I tried adding this line to the end of the file (knowing that you're not supposed to make manual edits):

If a PCI vendor ID (10ec for Realtek) and device ID combination is not recognized, you can make it get recognized at runtime with:

# echo 10 ec 8169 > /sys/bus / pci / drivers / r8169 / new_id

Example:

# lspci -s 04: -nnvvv
04:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL-8129 [10ec:8129] (rev 10)
Subsystem: Coreco Inc RTL8111/8168 PCIe Gigabit Ethernet (misconfigured) [11ec:8129]
Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort->SERR- <PERR- INTx- Interrupt: pin A routed to IRQ 3 Region 0: I/O ports at c000 [size=256] Region 1: Memory at f7b40000 (32-bit, non-prefetchable) [size=256] [virtual] Expansion ROM at f7b00000 [disabled] [size=256K] Capabilities: [dc] Power Management version 1 Flags: PMEClk- DSI- D1- D2- AuxCurrent=55mA PME(D0-,D1-,D2-,D3hot-,D3cold+) Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME- Kernel driver in use: pci-stub # echo 0000:04:00.0> /sys/bus/pci/drivers/pci-stub/unbind
      # echo 0000:04:00.0 > /sys/bus/pci/drivers/r8169/bind
      # lspci -s 04: -nnvvv
      04:00.0 Ethernet controller [0200]: Realtek Semiconductor Co., Ltd. RTL-8129 [10ec:8129] (rev 10)
      Subsystem: Coreco Inc RTL8111/8168 PCIe Gigabit Ethernet (misconfigured) [11ec:8129]
      Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
      Status: Cap+ 66MHz+ UDF- FastB2B+ ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort->SERR- <PERR- INTx- Latency: 32 (8000ns min, 8000ns max), Cache Line Size: 64 bytes Interrupt: pin A routed to IRQ 19 Region 0: I/O ports at c000 [size=256] Region 1: Memory at f7b40000 (32-bit, non-prefetchable) [size=256] [virtual] Expansion ROM at f7b00000 [disabled] [size=256K] Capabilities: [dc] Power Management version 1 Flags: PMEClk- DSI- D1- D2- AuxCurrent=55mA PME(D0-,D1-,D2-,D3hot-,D3cold+) Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME- Kernel driver in use: r8169
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The hardware of the system is arranged so that devices on the address bus will only respond to particular addresses which are intended for them, while all other addresses are ignored. This is the job of the address decoding circuitry, and that establishes the memory map of the system. As a result, system's memory map may look like in the table on the right. This memory map contains gaps, which is also quite common in actual system architectures. ,Memory hierarchy Virtual memory Secondary storage,I/O operations can slow memory access if the address and data buses are shared. This is because the peripheral device is usually much slower than main memory. In some architectures, port-mapped I/O operates via a dedicated I/O bus, alleviating the problem. ,PDP-11, an early example of a computer architecture using memory-mapped I/O Unibus, a dedicated I/O bus used by the PDP-11

Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing input/output (I/O) between the central processing unit (CPU) and peripheral devices in a computer. An alternative approach is using dedicated I/O processors, commonly known as channels on mainframe computers, which execute their own instructions.

Memory-mapped I/O uses the same address space to address both memory and I/O devices. The memory and registers of the I/O devices are mapped to (associated with) address values. So a memory address may refer to either a portion of physical RAM, or instead to memory and registers of the I/O device. Thus, the CPU instructions used to access the memory can also be used for accessing devices. Each I/O device monitors the CPU's address bus and responds to any CPU access of an address assigned to that device, connecting the data bus to the desired device's hardware register. To accommodate the I/O devices, areas of the addresses used by the CPU must be reserved for I/O and must not be available for normal physical memory. The reservation may be permanent, or temporary (as achieved via bank switching). An example of the latter is found in the Commodore 64, which uses a form of memory mapping to cause RAM or I/O hardware to appear in the 0xD000-0xDFFF range.

0xD000 - 0xDFFF
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In some cases, a ROM (BIOS) or similar will set up these registers on boot, but in other cases, the PCI controller is completely uninitialized and these translations need to be set up from the device tree. The PCI host driver will then typically parse the dma-ranges property and set up some registers in the host controller accordingly. ,This dma-ranges entry indicates that from the PCI host controller's point of view, the 512 MB at PCI address 0x00000000 will appear in the main core memory at address 0x80000000. As you can see we just set the ss address type to 0x02 indicating this is some 32bit memory. ,The advanced sample machine adds a PCI host bridge with control registers memory mapped to 0x10180000, and BARs programmed to start above the address 0x80000000. ,Each PCI bus segment is uniquely numbered, and the bus numbering is exposed in the pci node by using the bus-range property, which contains two cells. The first cell gives the bus number assigned to this node, and the second cell gives the maximum bus number of any of the subordinate PCI busses.

The device tree is a simple tree structure of nodes and properties. Properties are key-value pairs, and node may contain both properties and child nodes. For example, the following is a simple tree in the .dts format:

/dts-v1/;

/ {
node1 {
   a - string - property = "A string";
   a - string - list - property = "first string", "second string";
   // hex is implied in byte arrays. no '0x' prefix is required
   a - byte - data - property = [01 23 34 56];
   child - node1 {
      first - child - property;
      second - child - property = < 1 > ;
      a - string - property = "Hello, world";
   };
   child - node2 {};
};
node2 {
   an - empty - property;
   a - cell - property = < 1 2 3 4 > ; /* each number (cell) is a uint32 */
   child - node1 {};
};
};
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