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1. 요약·해설
원문의 핵심 논리와 kernel programming 관점의 보충 설명입니다. 아래의 전문 번역과는 별도로 작성했습니다.
2. 영어 원문 전체
번역 기준이 된 Linux v6.18.37 원문입니다. 줄 번호는 이 버전의 파일 좌표입니다.
원문 전체 펼치기
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Release Notes for Linux on Intel's IXP4xx Network Processor
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===========================================================
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Maintained by Deepak Saxena <[email protected]>
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-------------------------------------------------------------------------
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1. Overview
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Intel's IXP4xx network processor is a highly integrated SOC that
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is targeted for network applications, though it has become popular
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in industrial control and other areas due to low cost and power
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consumption. The IXP4xx family currently consists of several processors
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that support different network offload functions such as encryption,
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routing, firewalling, etc. The IXP46x family is an updated version which
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supports faster speeds, new memory and flash configurations, and more
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integration such as an on-chip I2C controller.
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For more information on the various versions of the CPU, see:
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http://developer.intel.com/design/network/products/npfamily/ixp4xx.htm
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Intel also made the IXCP1100 CPU for sometime which is an IXP4xx
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stripped of much of the network intelligence.
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2. Linux Support
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Linux currently supports the following features on the IXP4xx chips:
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- Dual serial ports
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- PCI interface
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- Flash access (MTD/JFFS)
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- I2C through GPIO on IXP42x
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- GPIO for input/output/interrupts
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See arch/arm/mach-ixp4xx/include/mach/platform.h for access functions.
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- Timers (watchdog, OS)
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The following components of the chips are not supported by Linux and
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require the use of Intel's proprietary CSR software:
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- USB device interface
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- Network interfaces (HSS, Utopia, NPEs, etc)
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- Network offload functionality
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If you need to use any of the above, you need to download Intel's
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software from:
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http://developer.intel.com/design/network/products/npfamily/ixp425.htm
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DO NOT POST QUESTIONS TO THE LINUX MAILING LISTS REGARDING THE PROPRIETARY
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SOFTWARE.
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There are several websites that provide directions/pointers on using
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Intel's software:
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- http://sourceforge.net/projects/ixp4xx-osdg/
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Open Source Developer's Guide for using uClinux and the Intel libraries
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- http://gatewaymaker.sourceforge.net/
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Simple one page summary of building a gateway using an IXP425 and Linux
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- http://ixp425.sourceforge.net/
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ATM device driver for IXP425 that relies on Intel's libraries
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3. Known Issues/Limitations
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3a. Limited inbound PCI window
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The IXP4xx family allows for up to 256MB of memory but the PCI interface
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can only expose 64MB of that memory to the PCI bus. This means that if
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you are running with > 64MB, all PCI buffers outside of the accessible
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range will be bounced using the routines in arch/arm/common/dmabounce.c.
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3b. Limited outbound PCI window
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IXP4xx provides two methods of accessing PCI memory space:
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1) A direct mapped window from 0x48000000 to 0x4bffffff (64MB).
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To access PCI via this space, we simply ioremap() the BAR
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into the kernel and we can use the standard read[bwl]/write[bwl]
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macros. This is the preferred method due to speed but it
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limits the system to just 64MB of PCI memory. This can be
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problematic if using video cards and other memory-heavy devices.
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2) If > 64MB of memory space is required, the IXP4xx can be
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configured to use indirect registers to access PCI This allows
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for up to 128MB (0x48000000 to 0x4fffffff) of memory on the bus.
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The disadvantage of this is that every PCI access requires
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three local register accesses plus a spinlock, but in some
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cases the performance hit is acceptable. In addition, you cannot
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mmap() PCI devices in this case due to the indirect nature
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of the PCI window.
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By default, the direct method is used for performance reasons. If
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you need more PCI memory, enable the IXP4XX_INDIRECT_PCI config option.
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3c. GPIO as Interrupts
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Currently the code only handles level-sensitive GPIO interrupts
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4. Supported platforms
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ADI Engineering Coyote Gateway Reference Platform
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http://www.adiengineering.com/productsCoyote.html
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The ADI Coyote platform is reference design for those building
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small residential/office gateways. One NPE is connected to a 10/100
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interface, one to 4-port 10/100 switch, and the third to and ADSL
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interface. In addition, it also supports to POTs interfaces connected
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via SLICs. Note that those are not supported by Linux ATM. Finally,
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the platform has two mini-PCI slots used for 802.11[bga] cards.
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Finally, there is an IDE port hanging off the expansion bus.
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Gateworks Avila Network Platform
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http://www.gateworks.com/support/overview.php
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The Avila platform is basically and IXDP425 with the 4 PCI slots
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replaced with mini-PCI slots and a CF IDE interface hanging off
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the expansion bus.
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Intel IXDP425 Development Platform
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http://www.intel.com/design/network/products/npfamily/ixdpg425.htm
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This is Intel's standard reference platform for the IXDP425 and is
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also known as the Richfield board. It contains 4 PCI slots, 16MB
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of flash, two 10/100 ports and one ADSL port.
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Intel IXDP465 Development Platform
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http://www.intel.com/design/network/products/npfamily/ixdp465.htm
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This is basically an IXDP425 with an IXP465 and 32M of flash instead
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of just 16.
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Intel IXDPG425 Development Platform
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This is basically and ADI Coyote board with a NEC EHCI controller
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added. One issue with this board is that the mini-PCI slots only
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have the 3.3v line connected, so you can't use a PCI to mini-PCI
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adapter with an E100 card. So to NFS root you need to use either
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the CSR or a WiFi card and a ramdisk that BOOTPs and then does
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a pivot_root to NFS.
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Motorola PrPMC1100 Processor Mezanine Card
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http://www.fountainsys.com
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The PrPMC1100 is based on the IXCP1100 and is meant to plug into
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and IXP2400/2800 system to act as the system controller. It simply
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contains a CPU and 16MB of flash on the board and needs to be
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plugged into a carrier board to function. Currently Linux only
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supports the Motorola PrPMC carrier board for this platform.
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5. TODO LIST
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- Add support for Coyote IDE
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- Add support for edge-based GPIO interrupts
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- Add support for CF IDE on expansion bus
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6. Thanks
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The IXP4xx work has been funded by Intel Corp. and MontaVista Software, Inc.
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The following people have contributed patches/comments/etc:
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- Lennerty Buytenhek
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- Lutz Jaenicke
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- Justin Mayfield
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- Robert E. Ranslam
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[I know I've forgotten others, please email me to be added]
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Last Update: 01/04/2005
3. 한국어 전문 번역
영어 원문의 문단 순서와 의미를 유지한 전체 번역입니다. 코드, 함수명, symbol과 URL은 원문 표기를 유지합니다.
Release Notes for Linux on Intel's IXP4xx Network Processor
1-7Intel IXP4xx network processor용 Linux release note이며 Deepak Saxena가 관리했습니다.
1. Overview
8-25IXP4xx는 network application을 겨냥한 고집적 SoC이지만 저렴한 가격과 낮은 power consumption 덕분에 industrial control 등에도 널리 쓰였습니다. family별로 encryption, routing, firewall 같은 network offload 기능이 다릅니다.
IXP46x는 더 빠른 속도, 새 memory·flash 구성, on-chip I2C controller 같은 높은 integration을 제공합니다. Intel은 network intelligence를 많이 제거한 IXCP1100도 한동안 생산했습니다.
2. Linux Support
26-64| Linux 지원 기능 | 비고 |
|---|---|
| dual serial port | 지원 |
| PCI interface | 지원 |
| flash access | MTD/JFFS |
| I2C | IXP42x에서 GPIO로 구현 |
| GPIO input/output/interrupt | `arch/arm/mach-ixp4xx/include/mach/platform.h`의 access function 사용 |
| timer | watchdog와 OS timer |
USB device interface, HSS·Utopia·NPE 같은 network interface, network offload 기능은 당시 Linux가 지원하지 않았고 Intel proprietary CSR software가 필요했습니다.
proprietary software에 관한 질문은 Linux mailing list에 올리지 말라는 문서의 명시적 경고가 있습니다.
3. Known Issues/Limitations
65-100inbound PCI window의 제한 때문에 IXP4xx가 최대 256MB memory를 지원해도 PCI bus에 노출할 수 있는 영역은 64MB뿐입니다. 64MB보다 큰 RAM을 쓰면 접근 가능한 범위 밖의 PCI buffer는 `arch/arm/common/dmabounce.c` routine으로 bounce됩니다.
| outbound 방식 | 주소·용량 | 장점 | 제약 |
|---|---|---|---|
| direct mapped | `0x48000000`-`0x4bffffff`, 64MB | BAR를 `ioremap()`하고 표준 `read[bwl]/write[bwl]` 사용, 빠름 | PCI memory 64MB 한계로 video card 등에서 문제 가능 |
| indirect register | `0x48000000`-`0x4fffffff`, 128MB | 더 큰 PCI memory 공간 | PCI access마다 local register access 3회와 spinlock 필요, `mmap()` 불가 |
기본값은 성능을 위해 direct 방식입니다. 더 큰 PCI memory가 필요하면 `IXP4XX_INDIRECT_PCI` config option을 켭니다.
GPIO interrupt code는 당시 level-sensitive interrupt만 처리했습니다.
4. Supported platforms
101-151| platform | 구성·주의점 |
|---|---|
| ADI Engineering Coyote | 소형 gateway reference design. NPE가 10/100 interface, 4-port switch, ADSL에 연결되고 SLIC 기반 POTS 2개, 802.11[bga]용 mini-PCI 2개, expansion bus IDE port를 가짐. POTS는 Linux ATM 미지원 |
| Gateworks Avila | IXDP425의 PCI 4개를 mini-PCI로 바꾸고 expansion bus에 CF IDE를 연결한 형태 |
| Intel IXDP425 / Richfield | PCI 4개, flash 16MB, 10/100 port 2개, ADSL port 1개 |
| Intel IXDP465 | IXP465와 flash 32MB를 사용한 IXDP425 계열 |
| Intel IXDPG425 | ADI Coyote에 NEC EHCI controller 추가. mini-PCI에는 3.3V만 연결되어 E100 adapter 사용 불가. NFS root에는 CSR 또는 Wi-Fi와 BOOTP 후 `pivot_root`하는 ramdisk 필요 |
| Motorola PrPMC1100 | IXCP1100 기반 mezzanine card로 IXP2400/2800 system controller 역할. CPU와 flash 16MB만 있어 carrier board가 필요하며 Linux는 Motorola PrPMC carrier만 지원 |
5. TODO LIST
152-157- Coyote IDE 지원 추가
- edge-based GPIO interrupt 지원 추가
- expansion bus의 CF IDE 지원 추가
6. Thanks
158-173IXP4xx 작업은 Intel Corp.와 MontaVista Software, Inc.가 후원했습니다. patch와 comment를 기여한 사람은 Lennerty Buytenhek, Lutz Jaenicke, Justin Mayfield, Robert E. Ranslam이며 누락된 기여자는 추가 요청을 보내 달라고 적혀 있습니다.
마지막 갱신일은 2005년 1월 4일입니다.
요약과 해설
ixp4xx.rst:1-173IXP4xx는 network offload SoC이지만 당시 open Linux 지원은 기본 peripheral 중심이었습니다. PCI direct window는 빠르지만 64MB로 제한되고, indirect 방식은 128MB를 제공하는 대신 access 비용과 `mmap()` 불가 제약이 있습니다.
성능과 address 공간 사이의 trade-off입니다.