Method and apparatus for a boot progression scheme for reliably
Contents
1. 65 6 to remove references to other boot images Processing is complete as indicated by process block 542 In view of the many possible embodiments to which the principles of our invention may be applied it will be appreciated that the embodiments and aspects thereof described herein with respect to the drawings figures are only illustrative and should not be taken as limiting the scope of the invention For example and as would be apparent to one skilled in the art many of the process block operations can be re ordered to be performed before after or substantially concurrent with other operations Also many different forms of data structures could be used in various embodiments The invention as described herein contemplates all such embodiments as may come within the scope of the following claims and equivalents thereof What is claimed is 1 A method performed by a system the method com prising loading a second boot image based on a current boot image identifying the second boot image and updating the current boot image to identify a first boot image after said loading and updating operations booting using the second boot image loaded during said loading operation and in response to identifying that a state of the system booted with the second boot image by said booting operation is not ok loading and booting the system using the first boot image based on the current boot image identifying the first boot image 2 A co2. boot using the current image the next image will be used The boot of the system is initiated in process block 508 e g the process illustrated in FIG 5B is executed Processing is complete as indicated by process block 510 FIG 5B illustrates a process for booting the system in one embodiment Processing begins with process block 530 and proceeds to process block 532 wherein the system is booted with the retrieved image such as that loaded in process block 502 FIG 5A Next as determined in process block 534 if the state of the system initialized with the boot image is not ok then the system is rebooted in process block 536 i e the process illustrated by flow diagram illustrated in FIG 5A is caused to run again to load the next boot image Otherwise a successful boot was performed and the image is functioning properly e g communicates with a prede termined network appliance or otherwise determined based on any other mechanism or criteria As determined in process block 538 if the currently booted image is continued to be used e g it is not a one time test image indicated by a flag or other mechanism then in process block 540 the current image indicator e g boot progression data structure in one embodiment is updated so that during a next boot the successfully booted image will be used Moreover in one embodiment the boot progression data structure is updated 20 25 30 35 40 45 50 55 60
3. the United States Patent and Trademark Office
4. SERVER FIGURE 1 116 U S Patent Jul 4 2006 Sheet 2 of 6 US 7 073 053 B1 SYSTEM LOADER 200 BOOT PROGRESSION BOOT DATA IMAGES STRUCTURE NETWORK INTERFACE FIGURE 2 U S Patent Jul 4 2006 Sheet 3 of 6 US 7 073 053 B1 BOOT PROGRESSION DATA STRUCTURE 300 CURRENT IMAGE PTR IMAGE N PTR IMAGE 1 PTR FIGURE 3 U S Patent Jul 4 2006 Sheet 4 of 6 US 7 073 053 B1 START 400 402 RECEIVE NEW IMAGE NO 406 UPDATE BOOT PROGRESSION DATA STRUCTURE FIGURE 4 U S Patent Jul 4 2006 Sheet 5 of 6 US 7 073 053 B1 START LOAD IMAGE INDICATED BY CURRENT IMAGE UPDATE CURRENT IMAGE TO INDICATE NEXT IMAGE OTHER IMAGES INITIATE BOOT WITH RETRIEVED IMAGE FIGURE 5A U S Patent Jul 4 2006 Sheet 6 of 6 US 7 073 053 B1 START LOAD RETRIEVED IMAGE 536 IMAGE STATE OK IMAGE UPDATE CURRENT IMAGE TO INDICATE BOOTED IMAGE AND POSSIBLY REMOVE REFERENCES TO OTHER IMAGES FIGURE 5B US 7 073 053 B1 1 METHOD AND APPARATUS FOR A BOOT PROGRESSION SCHEME FOR RELIABLY INITIALIZING A SYSTEM FIELD OF THE INVENTION This invention especially relates to system initialization procedures of communications and computer systems and more particularly the invention relates to a boot progression scheme for reliably initializing a system BACKGROUND OF THE INVENTION CPU based appliances such as routers are usually re
5. US007073053B1 az United States Patent 10 Patent No US 7 073 053 B1 Oz et al 45 Date of Patent Jul 4 2006 54 METHOD AND APPARATUS FOR A BOOT 6 529 966 B1 3 2003 Willman et al oc 710 10 PROGRESSION SCHEME FOR RELIABLY 6 643 781 B1 11 2003 Merriam 713 201 INITIALIZING A SYSTEM 6 757 838 B1 6 2004 Chaiken et al 714 5 6 826 710 B1 11 2004 Merkin etal we 714 6 75 Inventors Doron Oz Even Yehuda IL Eldad OTHER PUBLICATIONS Bar Eli Ramat Hasharon IL Rami Tamir Ramat Gan IL Kruse Robert L Data Structures and Program Design in C 1999 Prentice Hall Inc pp 50 54 73 Assignee Cisco Technology Inc San Jose CA Giga Byte BX2000 User s Manual Dec 20 1999 pp US 42 49 Notice Subject to any disclaimer the term of this cited by examiner patent is extended or adjusted under 35 Primary Examiner Chun Cao U S C 154 b by 567 days Assistant Examiner Mark Connolly 74 Attorney Agent or Firm The Law Office of Kirk D 21 Appl No 09 976 222 Williams 51 Int Cl GO6F 9 24 2006 01 Methods and apparatus are disclosed for a boot progression GO6F 13 177 2006 01 scheme for reliably initializing a system A boot progression G06F 11 00 2006 01 data structure is maintained to indicate which of multiple 52 US Gl niire 713 2 713 1 714 36 boot images should be initially loaded upon startup of the 58 Field of Classification Search 713 1 syste
6. e any type of mechanism including a computer or system or component thereof The terms task and process are used generically herein to describe any type of running program including but not limited to a computer process task thread executing application operating system user pro cess device driver native code machine or other language etc and can be interactive and or non interactive executing locally and or remotely executing in foreground and or background executing in the user and or operating system address spaces a routine of a library and or standalone application and is not limited to any particular memory partitioning technique The steps and processing of signals and information illustrated in the figures are typically be performed in a different serial or parallel ordering and or by different components in various embodiments in keeping within the scope and spirit of the invention Moreover the terms network and communications mechanism are used generically herein to describe one or more networks communications mediums or communications systems including but not limited to the Internet private or public telephone cellular wireless satellite cable local area metropolitan area and or wide area networks a cable elec trical connection bus etc and internal communications mechanisms such as message passing interprocess commu nications shared memory etc The terms first sec
7. e or more boot images 203 a manager 204 and a network interface process 205 The operation of these elements in one embodiment are further described in relation to FIGS 3 5 One embodiment of boot progression data structure 202 is in the form of a stack such as that illustrated by boot progression data structure 300 illustrated in FIG 3 As shown stack 310 includes one or more image pointers 311 319 which provide an address or other indication for loader 201 to locate a particular boot image Current image US 7 073 053 B1 5 pointer 305 e g top of stack pointer maintains an indica tion of which image pointer 311 319 should be used during a next boot operation As would be apparent to one skilled in the art embodi ments include a boot progression data structures imple mented in an unlimited number of ways such as but not limited to a stack pointers arrays ordered sets linked lists trees or using any other techniques mechanisms and data structures For example in one embodiment a boot pro gression data structure is implemented without using point ers Additionally a boot progression data structure 202 FIG 2 may be simply a current boot image pointer that is updated in a progression indicated by an ordered set of boot images maintained in any manner locally or remotely One embodiment of manager 204 FIG 2 is illustrated in the flow diagram of FIG 4 Processing begins with process block 400 and proceeds to pr
8. limitation Each of the claims individu ally recite an aspect of the invention in its entirety More over some embodiments described may include but are not limited to inter alia systems networks integrated circuit chips embedded processors ASICs methods and com puter readable medium containing instructions The embodiments described hereinafter embody various aspects and configurations within the scope and spirit of the inven tion with the figures illustrating exemplary and non limiting configurations As used herein the term packet refers to packets of all types including but not limited to fixed length cells and variable length packets each of which may or may not be divisible into smaller packets or cells Moreover these packets may contain one or more types of information including but not limited to voice data video and audio information Furthermore the term system is used generi cally herein to describe any number of components ele ments sub systems devices packet switch elements packet switches routers networks computer and or communica tion devices or mechanisms or combinations of components thereof The term computer is used generically herein to describe any number of computers including but not lim ited to personal computers embedded processors and sys tems control logic ASICs chips workstations mainframes etc The term device is used generically herein to describ
9. m System 100 may be part of a router or other communications or computer system or any other device In one embodiment system 100 includes a processor 101 memory 102 storage devices 103 and a network interface 104 which are elec trically coupled via one or more communications mecha nisms 109 shown as a bus for illustrative purposes Various embodiments of system 100 may include more or less elements In one embodiment system 100 receives a new boot image from boot image server 116 via a file transfer or another download process System 100 updates a boot progression data structure stored in a nonvolatile storage location in memory 102 or storage devices 103 During initialization system 100 loads this boot image and should it operate properly then the boot progression data structure is updated so that this image is used during future system initializations In one embodiment whether system 100 can communicate with update authorization appliance 115 is included in the determination of whether system 100 is operating properly Also in one embodiment system 100 is initialized via a bootp or other process which receives its image across network 110 and which boot image is used or requested is either managed by system 100 or by boot image server 116 In one embodiment network 110 may represent a local or internal connection e g cable bus to system 100 and boot image server 116 and or update authorization appliance 115 are external
10. m During a boot phase the boot progression data 713 2 100 711 170 714 36 structure e g a stack or other data structure is modified to See application file for complete search history indicate a next boot image to use upon a next startup of the system If the boot image provides a functional system then 56 References Cited the boot progression data structure is updated to once again indicate to boot with this image and possibly removing U S PATENT DOCUMENTS references to other boot images Otherwise a reset or restart 5 793 943 A 8 1998 Noll neseser 714 6 operation is performed to boot using another image In this 5 887 163 A 3 1999 Nguyen et al manner a remote system can be upgraded across a network 5 974 546 A 10 1999 Anderson VRSAR ESEESE 713 2 and should the upgrade not perform correctly the system 6 292 890 BI 9 2001 Crisan reverts to a previous boot image 6 317 827 BL 11 2001 Cooper iini 713 2 6 345 294 Bl 2 2002 O Toole et al 6 446 203 B1 9 2002 Aguilar et al we 713 2 10 Claims 6 Drawing Sheets START LOAD IMAGE INDICATED BY CURRENT IMAGE UPDATE CURRENT IMAGE TO INDICATE NEXT IMAGE OTHER IMAGES INITIATE BOOT WITH RETRIEVED IMAGE U S Patent Jul 4 2006 Sheet 1 of 6 US 7 073 053 B1 SYSTEM MEMORY INSTRUCTIONS DATA PROCESSOR STORAGE DEVICES INSTRUCTIONS DATA NETWORK INTERFACE UPDATE AUTHORIZATION APPLIANCE BOOT IMAGE
11. motely software upgradeable with the software image residing in some form of non volatile memory such as flash memory Updating the software image involves download ing a new image to the appliance and replacing the existing image with the new image To overcome a problem of a power failure or other failure during the downloading or flash update process a double image approach may be used However if the loaded image cannot successfully load or connect to other systems e g a management system for any reason e g hardware incom patibility network incompatibility defective image it is necessary to manually access the appliance and reload a workable image or downgrade the software However such an upgrade scheme is problematic especially in installations where there are numerous such appliances or the upgrade process is done remotely New systems and methods are required for initializing and updating the boot images of systems SUMMARY OF THE INVENTION Systems and methods are disclosed for a boot progression scheme for reliably initializing a system In one embodi ment a boot progression data structure is modified to indicate a boot order including to use a second boot image before a first boot image The system is booted using the second boot image In one embodiment a state of the system booted with the second boot image is identified and in response system is rebooted using the first boot image In one embodiment a state
12. mputer readable medium containing computer executable instructions for performing operations said operations comprising loading a second boot image based on a current boot image identifying the second boot image and updating the current boot image to identify a first boot image after said loading and updating operations booting using the second boot image loaded during said loading operation and in response to identifying that a state of the system booted with the second boot image by said booting operation is not ok loading and booting the system using the first boot image based on the current boot image identifying the first boot image 3 A method performed by a system the method com prising loading a second boot image based on a boot order identified by a boot progression data structure the boot progressing data structure including a plurality of indi cations at least one of the plurality of indications identifying the second boot image and at least a second one of the plurality of indications identifying a first boot image and updating the boot progression data structure to indicate a new boot order including to boot next using the first boot image after said loading and updating operations booting using the second boot image loaded during said loading operation and in response to identifying that a state of the system booted with the second boot image by said booting operation is not ok loading and booting the s
13. ocess block 402 wherein a new image is received such as via network interface 205 FIG 2 Next as determined in process block 404 if the image is corrupted processing returns to process block 402 to receive a next image Otherwise in process block 406 the boot progression data structure e g boot progression data struc ture 202 shown in FIG 2 boot progression data structure 300 shown in FIG 3 is updated to reflect the newly received image Processing returns to process block 402 to receive a next image Exemplary processes performed upon initialization in one embodiment such as by system 100 FIG 1 and or loader 201 of system 200 FIG 2 are illustrated in FIGS 5A B Processing begins with process block 500 and proceeds to process block 502 wherein the boot image referenced by a current image indicator is retrieved and loaded in to memory For example in one embodiment using the boot progression data structure 300 illustrated in FIG 3 the particular boot image retrieved is the one indicated by the particular image pointer 311 319 indicated by current image pointer 305 Next as determined in process block 504 if there are other images in the boot progression data structure e g the stack originally had more one entry the ordered list of the image progression is not empty etc then in process block 506 the current image indicator is updated to indicate the next boot image In this manner if the system is unable to
14. of the partition stack in accor dance In one embodiment the system uses watchdog timers and or other mechanisms to verify the integrity of the boot image and if a problem is detected a reset operation is performed to boot the system with a previous version In case the new software version is damaged or does not load for any reason the system will reset without updating the stack and the previous version will be loaded Optionally additional parameters may be passed to the software version through the same stack to enable other features such as one time or some other predetermined number of times software testing with automatic down grade in any case e g a flag that will instruct the version not to re write the partition stack etc In this manner certain embodiments may be upgraded and or tested and should the new boot image not produce a functional system the system will automatically revert to a previously working image without physical intervention which could be especially difficult and costly for remote systems In addition multiple boot images representing different software versions and or configurations could be 20 25 30 40 45 50 55 60 65 4 preloaded into a system with the system progressively sequencing through these multiple boot images until a working system is produced FIG 1 illustrates one embodiment of a system including a boot progression scheme for reliably initializing a syste
15. of the system booted with the second boot image is identified and in response the boot progression data structure is updated to indicate to boot next time with the second boot image In one embodiment the boot progression data structure includes a stack BRIEF DESCRIPTION OF THE DRAWINGS The appended claims set forth the features of the inven tion with particularity The invention together with its advantages may be best understood from the following detailed description taken in conjunction with the accom panying drawings of which FIG 1 is a block diagram of an embodiment for a boot progression scheme for reliably initializing a system FIG 2 is a block diagram illustrating a few of processes and maintained data structures and boot images in one embodiment FIG 3 is a block diagram of an exemplary boot progres sion data structure FIG 4 is a flow diagram of an exemplary process for receiving a new boot image and for initializing the boot progression data structure and 20 25 30 35 40 45 50 55 60 65 2 FIGS 5A B are flow diagrams of exemplary processes used in one embodiment for implementing a boot progres sion scheme DETAILED DESCRIPTION Methods and apparatus are disclosed for a boot progres sion scheme for reliably initializing a system Embodiments described herein include various elements and limitations with no one element or limitation contemplated as being a critical element or
16. on data structure is updated to once again indicate to boot with this image and possibly removing references to other boot images Otherwise a reset or restart operation is performed to boot using another image In this manner a remote system can be upgraded across a network and should the upgrade not perform correctly the system reverts to a previous boot image In one embodiment including a networked system the flash memory is divided into two or more partitions to accommodate multiple software images partition 0 n In addition a space will be reserved to hold a stack of partition numbers for the boot loader containing from which parti tions to load the software image and possibly other boot instructions Upon boot the boot loader will examine the progressive boot data structure in the form of a stack and will pop the last entry in the stack and load the image appropriately The first bottom oldest entry in the stack cannot be popped Upon completing the process of downloading via a network peripheral device or other mechanism a new software image is copied into a partition and the partition number will be pushed into the stack and therefore this new software image will be run upon the next reset In one embodiment the software image that is loaded will be responsible to decide whether it has sufficient control of the system e g a positive connection to a management station has been established and updating
17. ond etc are typically used herein to denote different units e g a first element a second element The use of these terms herein does not necessarily connote an ordering such as one unit or event occurring or coming before the another but rather provides a mechanism to distinguish between particu lar units Moreover the phrase based on x is used to US 7 073 053 B1 3 indicate a minimum set of items x from which something is derived wherein x is extensible and does not necessarily describe a complete list of items on which the operation is based Additionally the phrase coupled to is used to indicate some level of direct or indirect connection between two elements or devices with the coupling device or devices modify or not modifying the coupled signal or communi cated information Moreover the term or is used herein to identify an alternative selection of one or more including all of the conjunctive items Methods and apparatus are disclosed for a boot progres sion scheme for reliably initializing a system A boot pro gression data structure is maintained to indicate which of multiple boot images should be initially loaded upon startup of the system During a boot phase the boot progression data structure e g a stack or other data structure is modified to indicate a next boot image to use upon a next startup of the system If the boot image provides a functional system then the boot progressi
18. or internal to system 100 In one embodiment boot image server 116 and update authoriza tion appliance 115 are located within a single system or process The operation of system 100 is typically controlled by processor 101 using memory 102 and storage devices 103 to perform one or more tasks or processes Memory 102 is one type of computer readable medium and typically comprises random access memory RAM read only memory ROM flash memory integrated circuits and or other memory components Memory 102 typically stores computer execut able instructions to be executed by processor 101 and or data which is manipulated by processor 101 for implementing functionality in accordance with the invention Storage devices 103 are another type of computer readable medium and typically comprise solid state storage media disk drives diskettes networked services tape drives and other storage devices Storage devices 103 typically store computer ex ecutable instructions to be executed by processor 101 and or data which is manipulated by processor 101 for implement ing functionality in accordance with the invention As used herein and contemplated by the invention com puter readable medium is not limited to memory and storage devices rather computer readable medium is an extensible term including other storage mechanisms FIG 2 illustrates one embodiment of a system 200 including a loader process 201 a boot progression data structure 202 on
19. ulting in the system operating in an active state the boot progres sion data structure is updated to identify the first boot image to use during a next boot phase 9 The system of claim 7 wherein in response to the system operating in an active state when booted with the first boot image the boot progression data structure is updated to reflect only the first boot image 10 An apparatus comprising means for loading a second boot image based on a current boot image identifying the second boot image and updating the current boot image to identify a first boot image means for booting after said loading and updating opera tions using the second boot image loaded during said loading operation and means for in response to identifying that a state of the system booted with the second boot image by said booting operation is not ok loading and booting the system using the first boot image based on the current boot image identifying the first boot image UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT NO 7 073 053 B1 Page of 1 APPLICATION NO 09 976222 DATED July 4 2006 INVENTOR S Oz et al It is certified that error appears in the above identified patent and that said Letters Patent is hereby corrected as shown below Col 7 line 5 replace profession with progression Signed and Sealed this Twenty eighth Day of November 2006 om WE ae JON W DUDAS Director of
20. ure including a plurality of indications at least one of the plurality of indications identifying the second boot image and at least a second one of the plurality of indications identifying a first boot image means for updating the boot order identified by the boot progression data structure and means for booting using the second boot image wherein said means for updating the boot order includes means for determining whether to load and boot next time with the second boot image or whether to load and boot next time with the next boot image specified by the boot order based on a value of a boot times indicator identifying a number of times to load and boot using the second boot image wherein the first and second boot images are operable images 20 25 30 35 8 7 A system comprising a boot progression data structure indicating an ordering of a plurality of boot images wherein the boot progres sion data structure includes a plurality of indications of boot images and a loader responsive to the boot progression data structure wherein the loader loads a first boot image identified by the ordering ofthe plurality of boot images and updates the boot progression data structure to identify a next boot image in the ordering of the plurality of boot images and then boots the system with said loaded first boot image 8 The system of claim 7 wherein in response to said booting the system with the loaded first boot image res
21. ystem using the first boot image based on the new boot order identifying to boot next using the first boot image 4 The method of claim 3 wherein the boot progression data structure includes a stack including the plurality of indications and for identifying said boot orders US 7 073 053 B1 7 5 A computer readable medium containing computer executable instructions for performing operations said operations comprising loading a second boot image based on a boot order identified by a boot profession data structure the boot progressing data structure including a plurality of indi cations at least one of the plurality of indications identifying the second boot image and at least a second one of the plurality of indications identifying a first boot image and updating the boot progression data structure to indicate a new boot order including to boot next using the first boot image after said loading and updating operations booting using the second boot image loaded during said loading operation and in response to identifying that a state of the system booted with the second boot image by said booting operation is not ok loading and booting the system using the first boot image based on the new boot order identifying to boot next using the first boot image 6 An apparatus comprising means for loading a second boot image based on a boot order identified by a boot progression data structure the boot progression data struct
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