BACKGROUND

|6ββ1| Today's computing odd Is facing an evergrowing am un of data -oe rocessed. S iRe ©stimaiss pedic that overall data will grow by SO tjimes by WW. Ibs data: is oftentimes tfw tm of high ^' def lllon gra hs^ ao ple applications, embedded sensors, media files, oommunjc ion traffic, and the ike.

002 Addition ll , today's computing worl is fe ing a user with an Increased expectation with re ar to latency., t ^' n ^rtl uf ,- «¾ m at becoming less and fess- p-atserst, an ex ect com uting systems to rovide i»s*¾¾s in a neal Ihsla t&t^ws. •manner.

pOflSj To address these em nds, some computer archiieeiore designers are outfitting nigh-end computing systems ik® oksatio s and servers win more than one processor, rs ma y oases, these -additional ^' processors arc optional so the user cars customize their computing system based on t alr- specific preferences, workload, and udget.

Examples are describe th fei!e isg detailed description and in eferen e to the drawings, in which;

OOS] F¾.. 1 depicts -an -example- computing s stem in accordance with an aspect of the present disclosure;

pGM;l Fig. depicts an example process ^' H w diagam fo operation of the computing system depicted in Fig, 1 In accordance wit an aspect of the present disclosure;

p0O?j Figs.3A- and -SB depc ¾«ottw example. <E¾mpu8ng system in; ccodance with an aspect of. the present sclosure where system firmware is u lised t control aspects of the. multiplexe, first us conrolte, and/or second bus controller; and

pf»S| Fig.4 depicts another example- rooess flow diagram for o rate of the ^■ computing system depiced I Figs,.3A and 3B in ccordance _. witn an aspect .of the present disclosure.. OSS] Certain temjs are used throughout the following description anil c ims to refer to particular -system compone ts. As on sk ed .in the art wi a reciate-, technology companies ma refer to components by different names. T is document does not intend to distnguis etes-sn com nents th differ to name but not function, \n the following ^' discussio an in .ti claims, i terms Ineludino and ^* «>mpdsl{¾* ar ysed: in an open*erjded fashion, and to should P-e imetpreted to mean "i cluding, but o tested to,.., , ^* Also,, the term "couple ^* .or ^cou les ^* is Intended to- mean either an indrect or direc connection. Thus if a irst -device couples -to a second devkss, that connectio may e through a drest afeetdsai or mechanical connectio , through an Indirect electrical or mec anical connection via other d vices and connections, through m e ical electnoai cpnneoon or hroygh a wireless electrical connectio ,.

imm&l Additionally, the term TSus controller is intended to mean a device that anag . c®mmunicafo.n o a bus.. For exam le, the devise may be a root -complex device, a d therefor© connect a pr cessor asnd memory Subsystem to an I/O a nd generate transaction re ess o isehaif of the processor.: which is interconnected through a local bus.. Moreov r, the term ^ dttipeer" is Intended to mean a devc that selects on® of several enaiog/dioMai Inputoutput stg als es and connects the selected signafiane to a single inputfouiput signai/¼me- In addition, the term "tone ^* is -intended to mmn a stream for imnsporiino; date. For example, t e lane ma comprise two differential signaing pairs, where each pair is used as a halt-duplex byte stream, transporting data packets in one direction ^' (|,e,, the lane is full-diiptes and each differential pair is haMpolex), Furthermore.: the term "slot ⁵ Is Intended to mean a bos or expansion ^' slot tha allo s additional boards (e.g., a video card) to be con ecte to a olhsfboars ^" or riser board. The slot may be, for example, a Pedpheral Component Interconnect (PCi slot Perip erai Component Interconnect Express <PCIe) slot, .2 slot, SFF-S63S pert, or Accelerated Q pbm Port. (AGP) slot.

£PQQi1J As- mentioned ^' above, some h¾tve d -computing systems Hike workstations and servers o have the option to incorporate mors than one processor on the mdherbosfd. 0ive« oday ⁴ * muiti-eona architectures, t i ovides the a ility to have numerous processing cores working In parallel For examl , two 12-core processors In a or kstahon can place 24 corss si the user's disposal to ia idly oiidiici complex tasks ¾f? povide sigri cafit computi g power.

|O01 £| Although t ere are ·®ί@π5ί| ¾πί de effe to the rdu!tiHprOcessof ar chitectu re, an issue has arisen dye to he optional nature of the additional processors). In particular, computing systems such as workstations, servers, a d desktops often include if5pu¾¾yl yt (!/O) of ex an ion slot that allo ses: to. lug-in a variety of cards {e.g.., graphics nd memoy cards) I© configure the system to meet ¾i ir needs. The slots are ©¾ert industry .standard interfaces, such m PC POle, InfiniBand, Rapid IQ _S HyperTrati sport, Cfe skPaih interconnect fQPI), or Starfaohe, Md mr, t e slots generally interact with a bus controler (e,g,, a root complex device In the eas of PCSe that controls the lanes- betw en the its controller and slat.. I is bus controller, however, :may be located -w tfr*- he processor, and this -processor may be optional in some architectures, as mentioned above. As a result, hen- the optional processor is not installed, the slot - hich uld ther is ha e m Interacting with the -controller wM the processor Is rendered nonfunction l. The same is tru when the controller is not located wtth the optional processor, but Is. mtner located within another optional component (e.g ., within the chipset) or as an optional stand-alone component

f ©£161:33 As discussed In greater ^■ d test beo wfth reference to various examples end figures, aspects of the present disclosur address at least the above-nientioned issue by providing an approach to make the slot {or other system componen functi n l even an the corresponding and optional processo;rco;ntroSer not installed. Hence, a slot or other system component that would have been re deed npn-ftinctlonaS

expandability nd utilization of the system,

|8&814J to one exam le! In accodance with an aspect Of the present disclosure, a compui g system is provided, The computing system som hses ^' a first bus controller to control X bus anes, a second bus _. controller to control Y bus lanes,, a 2 o X lane n lfiplexer, and a ¥ lane s stem ^' compon nt, w re Y > X ^' © _> X lanes from the Href bbs controller are coupled to the 2-to-1 X lane multiplexer. X lanes from the second bus- ^' corner ace eoupfed -to the -2-to- X iarse multiplexer, and ¥ - X lanes f m the second bus controller are coupled directly to the Y lane system component Additionally, X lanes from the ¾ o>1 X lan multiplexer am coupled ^' to the Y iahe s stem component. In one implementation, the ¾-to-1 X lane multiplexer is to select det een the lanes from the first, bus controller and the lanes from the second bus. controller based on whether the second bus controller Is present within the computing - system. Additionally; in some Implementatio s, a first rocessor comprises She first us controller, and a second roc ssor comprises the second bus controller, where the first roc ss- or is fixed within fh-e system end the second processor S optional witl ti the system,.

©©1S3 in another example In accordance with the present disclosure, ano er co puting; system is provided. The comput ng system cor rises a first bus controller to cont ol X bus lanes, a second bus controller to control Y bus lanes (where Y > X > .0), a 24o~i X lane multiplexer, a r (arse slot, and system f rmware (e.g., SlOSiUEFl) to control operation of least one of the 240-1 X lane multiplexer*, the first bus controller, and t e seco d bus controller. X lanes from t e first bus controller are coupled to the 2- tb~1 X Sane multiplexer. X lanes from the second bus controller are coupled to the 24o~1 X lane multiplexer _> and Y ~ X fanes torn the second bus controller are coupled directly to the Y lane slot, X lanes from the ¾4o~1 X. lane multiplexer are coupled to the Y lane slot. In one imple-mentattan, the system firmware is to control the 3-1 X Ian® multiple er to select the lanes received from the first bus controller,, and further control the second b controller to disable the Y - X lanes f om the second bus controller that are coupled lrec% ^' fo ie Y lane slot In anthe im lementat o ;, the system fi mwa e is to control the 2 0-1 X lane multiplexer to select the X lanes received from the second bus cont oller.

pBBI ^' SJ In yet another e am le in aocor ance wi the present disclosure, another comp ting System is pr vded. The computing system comprises a mandatory bus controller , an optional feus controller, a 240-1 multiplexer, and a: system component. The 2 o*1 multiplexer is coupled to the mandatory bus controller, and the 24o-1 maiptexer Is also coupled to the optional bus controller. The ystem component is coupled to the 240-1 multiplexer, and the system component is also coupled directly to the optional bus controller. O erates of the 24o*t multiplexer and the ptional bus cont o le are controllable via a system ^" firmware to enable the system component to Interact with bus lanes from either the mandatory bus controller or the optional bus .controller,.

pfJQ17 Turning, to. Fig, 1 _t this figure depicts an example computing system 1.00 In accordance with an aspect of the present disclosure, More specifically, Fig. 1 depicts e ^• computing _. - system architecture wherein the system component 140 ^' remains, furic*?©«al and interacts with bus lanes f om eithe the first bu controller 1 0 or the second bus controller 120 de endi g on whether the second bus controller 120 Is installed. That is, the sys m component 140 is mi rendered n©ti4unct onal due to the -second bus controller 20 net being Ins tailed In the computing system 100. 100083 he competing s stem: 100 may -.be, for ex ple, a desktop, workstation, ]¾pi¾p _s scsen fic insimrnent, gamins sleviee, tablet, MO mp, television, detach ble f feletiapfop, ser er, retail point of sate de ice, smartphone, or other similar cernputhg system. The c m uting system 100 comprises a: first bus controller 110, a second b s centrotef 120, a rmi&ip!exer 130, and a system component 140 (east* described In greater detail below), ft should he readily apparent t at the system 100 Is a generalized lustration and fiat other elements maybe added or exisi g elements may fe -removed, odified, or rearra ged without de rti g fr m the scope of Sne present disclosure. For examp , fe corn u&ig system 100 may Ind-ude other component eornmon to a computing system such as _? for ©xsm ie,: a net ork Interface., a fan, m optical drive, a m«mofy device, a power supply, a motherboard, or the- like,

OOISJ Looking no at the first bus controller 110 a d the second bus controller 120, hese c mponents manag communicaio with at least the system component 140, For example, when the system component 140 comprises a FCIe I/O slot, th first !bus controller 110 and the second bus controller 130 act -as root complex de ices. The first bus controller 110 and the secon bus- controller 120., therefore, may eorsnect the processor and memory subsystem (not shown) to the PCfe I/O slot 140, and generate ransecti n requests On ehalf oi the processor, w-hich is- interconnected th to gh a local :bus,

IQWM Dependng o m implementation, the first bus controller 110 and/or -second ^' bus controlle 120 may e discrete devices, or may be integrated wSriio a processor, chipset, and/or other component {no shown), in some examples, the second us controller 120 ^' Is an optional componen within the computing system 100 fand therefore shown In doted lines In Fig, 1) a d the first us controller 110 Is a fixed compon n within the c mputing system 100 ( nd fherefore shown; in solid lines In Fig,. 1). T is may be. because tne second bus controller 120 Is integrated within an optional processor or ether optional component © ,, _< a _. chipset) of the c m eing; system 100. This may-ajso ^' .bebecasise ^' the second us con oller 120 is a _. discrete- eoropo em tet is optional within the compiling system 1Q0.

[000213 In various example^ the second bus controller 20 controls moffi bus lanes than t e firs feus controller 110, For example, in o e implementation, the second bus controller 1:20 controls Y lanes and the first bus controller 110 controls X ye a es, here Y > > 0, More specifically, in o e implementation., the second bus controller 120 controls 8 bus tenes and the first bus controller controls 1 bus lane, in anothe implementation, the second bus controSer 20 controls 4 bus lanes and the first fens - 8 - controller 110 controls 1 us lane. Furthermore, In another fmp&wniatkm, tie -second" ! u s controller 120 coni- is e $us lanes and the first bus controller 1 0 controls 2 bus

|©©0¾¾J Turning now to the multiplexer 130, this component selects one of several analog digital input/output signals or fanes and connects ^, the friput output aignai ian o a single input/output slgnai lane. Fo example, the mwf few 130 can select one of two l nes received from ine first bus controller 0 and second bus controller 20 nd couple trie selected lan a the s stem component ^" 140. In some xamples, operation of t e multiplexer 130 is eontf iteb by internal logic. In otter examples, ©peratioR of the multiplexer 130 Is c-ontroite- by a basfc m utis^tpu system plOS) OF a unif ed e tensi le firmware inte lace- (U€Pi) of the computing system 100. in yet further exa les _* the ultiple e SO includes l¾ic to sense whether the second bus controller 120 s present, and conducts operations ased at Seas! in par on i sensed condition,

f 00023] looking now at the -system component 140, this component imy be an I/O or expa sio slot in various, examples. For exam l , the component may be a PGte slot, accelerated graphic port (ΑΘΡ) stot FCI s ot M.2 slot, SFF-8639 port, or other sim lar expansion slots, in other examples, the system, component 140 may .be another component on the -rnotheroaar . such as a storage controller, network -controller, -graphics

Co troller, etc _*

0024J Mo looking at the whole system fOO. ehown in Fig, 1, as mentioned at ove _? this architecture aoaoles the system componen 140 to remain funcilsnal and Interact with l nes im e&her the first bus controller 11 ^' D, or the econd bus o ntro-ifar 120, depending m wheth r the second bus controlle 120 is installed, As depicted i Fig.: 1 , the first bus controller 110 is to control X b s imm (e.g., 1 bus fane}., and the second feus controller 120 Is to control Y bus lanes (e.g., 8 feus fanes), where Y X > 0. The X lanes (e.g., 1 iane) from the first bus eootrafer 110 a e coupled to the 2-fo 1 X Ian® m itlpfexer 130, in addition, X lanes (e-.g-,, 1 lane) from the second bus controller 12 ar coupled to the 2 ^« *M X lane multiplexer 130 _* and Y - X lanes (e.g., 7 lanes) from the second bus controller are coupled directly to t e Y fane s stem: component |e.g, _r a RCIe slot),

|0002S| Given the abov^ entsoned configuration, when the second torn contro-te 120 is present, the multiplexer 13Q senses, the second bus controller 120 is present and selects the X lanes from trie s cond bus controller 120., and this selection In corobinaton with the Y X lanes direeiy coypied between the second bus controller 120 and the system component 140 _s e a les the second feus contraiter 120 to Interact wi h the system component 140, in the case when the system comment O is a Y l ne slot (e.g.,, Y a © PCte sfot), configuration ena&tes e second bus controller 12 t control each of the Y anes on the Y lane slot,

S02S] By contrast, hen the second bus eontrofer 128 is not presen the iR uJ s i xof 30 s oses th# second bus controlle 120 Is ot present and selects the X lanes from the first bus controller 1 0, and this- selects enables the first PUS controller 110 to Interact with the sys em component 1 0: and control H e lines therebetween ^' , in t e case when the system component 140 Is a Y lane slot (e,g, _f a Y lane FCIe slot), the configuration ^'' enables the Srsl bus- controller 110 to control X lanes on the Y Ian© slot, and sill be render d functional per, e,g, ₅ the a specification wnich allows for example a x0 slot to operate as a xl slot an Interactin with a xt controller,

|β£¾2?] Turning now to ¾, 2, this figure depicts a process Sow diagram 200 for the -computing sys em 100 depicted In Fig, 1 In accordance with an aspect of the present disclosure. It should h readily -apparent that the processes depleted ^' In F¾, 2 represent generalized lustratfons, and thai other processes mm fee added <sr ex sting processes may be removed, modified, or rearranged without departing fern the scope and spirit of the present ^' disclosure.. Additionally, It should he understood that the processes may represent functions and/or actions performed y drey its or logic associated with at least one system component {«;§-., a multiplexer,, slot, end/of contro8er _* Furthermore, ¾, 2 Is not intended i® limit the implementation of the described processes, but rather the %ure illustrates functional info mation o ¾B skilled In the art could use to dssign fsbtieate circuits, generate machine-readable instructions (e,g:,, software, f rm are:, etc,), or use aombi a i of hardware and software to perform the illustrated processes.

$mm} The process 200 may begin at block 2 0, where a determination is made as to ^hetf the second bus controller 12Q Is present. I en example, this- determination Is made - by the multiplexer 130 v¾ logic and/or a sensing ^' functionality,. At !hloc 220, m es onse to determining that the second bus controller 120 is not resent the multiplexer ISO selects the X lanes torn fie first feus- controller i 10, Thereafter, at block 230 the system .component 140 (e,g, _s . a PCIe slot) operates as an X lane system component e,g.., operates as a xt PCIe slot when X « land the system component is . ^' a PCI* slot).

immm By contrast at block 240, In esponse to de ermining that, the second feus controller 120 is rese t, t e multiplexer 130 selects the X lanes from: the second -bm controlle 120.. Thereafter, at bloc* 250, the system component 140 « PCIe slot) operates as a Y lane :s stem ^' comport operates as a ^χ § PCfe sot hen X ~ i end Y - S) in espo se w the selecion by t e multiplie 130 and the directly cou led lanes fiorn the second bus. controller 120. Accordingly > the syst co onspi 140 .operates as Y lane ex o ent iRteras g with the second b $ controller 20 when the second bos ©ontfofiar 120 is present, nd as en X lane system component ntersellng fth the first us m ©Iter 1 0 whan the seoond feus ppntroSfer 120 is not pesent Hence, among other things, the taove-dlsoussed issue of a system com o nt rendered pan-fu ettonai due to the a sence of a espective co our is resolved,

OO I oving on to Figs, 3A and 3B. _: t ese figues depict another exam le com uting system 300 in accordan s wth a different aspect of the present disclosure, fn particular, the architecture shown in Figs, 3Λ and OB are imilar to g.1,. but syst m firmware 310 is coupled to and controls as ects of the .multiplexer 130, irst ts s controller 110 andor second bu eohirotter 0, The system firmware 310 may c¾>mpnse _; for example, a paste fnpt ©uiput system (BIOS) or e unified extensible rniware interface (UEF!). The system firmware 310 controls the multiplexer 130 to select lanes ton first bus controller 110 or second bus controler 120 based on user preference and not based solely on whether the second bus controller is sensed 120. That , even if the secon b s controller SO Is present, the m ltiple er 130 may sii select the lanes torn the first bus controller 110 and therefore the irst bus controller 110 would nternet wit h fee system component 140 s opposed the econd bus controlier 120, This may b usetol i situations -such as. _: fer example, when the Irst bus controller 110 is a 6EN3 X lens component and the second bus controller 120 Is- a GEN2 Y lane esrnponeni w ere Y > X > 0, In his situation, t e seeofld bus controller 20 may control more lanes but the first bus controller 110 may have faster fanes,

f»31:| T m, and refering to fig, 3A, if a mm prefers to utilise the f er faster fanes of the first bus controller 110, the user may m sstem irrmvare 310 to control the m ltiplexer 130 to select the X lanes torn the irst bus controller i lfj. In addition, the system firm are 31 Q may control the second bus controller 120 to disable ai least the Y- X lanes directly coupled to the system component 0. 1 ould fee noted that dsabling the X lanes ©f the sec nd hue controller 120 would be optional ecaus the multiplier 130 would not be selecting these lanes in this scenario.

0032 B contrast and referring to Fig. S , If a se prefers to utilize the more numerous bust slowe lanes of the second bos controller 120, the user may utilise system firmware 310 to control the multiplexer 130 to select the X lanes fom: the second bos controlle 120, In addiion, the sysfem firmware 310 may control the first bus controller - θ -

120 4 Ift X tones torn the fir t us controller 1», It shouie! be ed that disabling the X lanes _, of the first has coratoiier 110 would be optional peea«$e the multiplexer 130 ould n t be selecting these anes ih this scenario.

©0333 urning now to Fig, , this figure depicts a process l w diagram 400 for the com uing system 300 de iced m RgsvSA _. and ^' 38 n accordance wit? so aspect of t e present disclosure, it should be readily apparent thai tha i cosses depicted in Fig. 4 represent generated Illustrations, _: , nd that other processes ma.y be added or existing r cesse n / b removed;, modified, or earie ge! wliheyt departing from the scope and spirit of the present disclosure, -Fiir ei It should be. understood tha the- processe may e esent ex cutable I stru tion stored n a .memory {e,@, _:f a Sash memory device that may causa a component Ike the multiplexer 130, first bos controller 1 0, and/or second bus. controller 120 to responds to periorm actions, to change states, acdfe to alee d cision .- Thus, th described processes may ba Im lemented as executable instructions and/or operations provided by a memory ass ca d with a com eting system 300. Aternately or In addition, tha processes may represent functions and/or actions performed by circuits- or logic ass ciated with at toast one system component (e.g., a multiplexo, slot,,, and/or controller). Furthermore, Rg.4 is not intended to limit the im lementati n of tha described processes., but rather the Igwre illustrates funciiorsai lofefrnstion one skilled In the art could use to des!QO/fatericate circuits,: generate machine-readable Instrucions {e.g,, software, fimware, etc.), or «se a comblriailon of hardware and sof e to perform the iustrated processes.

OES J The process 400 may begin at block 41 Q, _: where a - ecision Is mad as to whether the first bos controller tt.0 is to internet or otherwise cou le the busianes with the system component 140, As meniionei above, this may be the case when the first ! us contrsiler 110 Is a ;GEN& X iarte .component, end the second bus conroler 129 as a Y fens component, where. Y > X 0, and hence the secon bus csnroier 120 may control more anes but th first toys controller 110 may have faster la s,

£0003$ If a determination is made tha the first boa controller 1 T Is to Interact o otherwise couple the buta es with the system component 140, at block 42Q, the system firmware 310 is to cause the mu¾ le«er 130 to safest the X lanes received from the first hm controller 110. Additionally, at Stock 430, the system firmware 3 Q is to ^■ cause the second us controller 1:20 to disable at east ^' the Y- lanes directl coupied to the system compo ent 140, As ¾ result -at. block 440, the system component: 140 operates as an X lane component Interacting with the first bus controller 10.. 1000363 B con ast f t¾e cletermWo« Is w te thai the first bus controller 110 is to not M w otherwise όκ . the busin ss with t e system com one t im, bfcok S0 _S the system flnriw&fe 3-10 is to cause the-rn-ufliipifexer 130 to select the X ianes from the second ^' b-us-bonsmlfef 120, As a result, at block.460, the s stem cm nent 140 o erates as a Y fans component Interacting wth the second bus c-ontroifer 120. Henc , the user las the ion to select whsch controller ^' interacts with the sstern component 1 0 _y a d therefore otsrnialiv ake adv ntage: ©fib© fact thai a controller may have cfei&ss. sod/o faster/slower lanes,

0©3? The fogoing provides arious examples wttteh address at least the issue of & system component being rendered nonfunctional due to. the absence of a corres onding controller., Moreover, the foregoing provides various examples ich r ide the user with the capability to determine which controller interacts- or othewise cou les the tjuslawes with irte system component when resfjeciive corresponding controllers are pr sent. As one of ordinary sm would understand, the -sol ^' yion does so in a- cost effective manne, ¾nd spedficaliy ena es ine multiplexer to only have to support the um er of lanes associated with the .controller which supports less l nes. For example, if the first bus controller controls 1 lane and the second bus controller contols 8 lanes, a- 2-to-1 muMplexer that is 1 lane wide ould he appropriate for the architecture d scibed in the present disclosure. Similarly, If- the first bus controller eor ots-2 lanes and the second bus -controller control S lanes, a 2-to-1 multiplexer that is 2 lanes wde would be appropriate for the arc eeiiife described in the present disclosure.. Among, other things., this may educe cost -due to use of- a arrower, So er* cost multiplexer.. I*? addition, this my reduc ^' the footprint of the multiplexer,

1660383 White the above disclosure has been show en described with reference to the foregoing examples.. It should he derst o that other forms, details, and impfementatlons may be oia e without depati g from the spirit and scope of the disclosure that is defi ed in the followi g claims.