Dell PowerEdge T710 Owner's manual

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DeployingUEFI

‐

AwareOperating

SystemsonDell™PowerEdge™

Servers

ByAnandJoshi,BillMunger,MarkShutt,

ThomasCantwell,andJohnSieber

 Pageii

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THISWHITEPAPERISFORINFORMATIONALPURPOSESONLY,ANDMAYCONTAINTYPOGRAPHICALERRORSAND

TECHNICALINACCURACIES.THECONTENTISPROVIDEDASIS,WITHOUTEXPRESSORIMPLIEDWARRANTIESOF

ANYKIND.

©2009DellInc.Allrightsreserved.Reproductionofthismaterialin

anymannerwhatsoeverwithouttheexpress

writtenpermissionofDellInc.isstrictlyforbidden.Formoreinformation,contactDell.

Dell,theDELLlogo,andtheDELLbadge,andPowerEdgearetrademarksofDellInc.Microsoft,Windows,Windows

Server,andActiveDirectoryareeithertrademarksorregisteredtrademarksof

MicrosoftCorporationintheUnited

Statesand/orothercountries.;SUSEisaregisteredtrademarkofNovell,Inc.,intheUnitedStatesandother

countries.

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Table of Contents

History...................................................................................................................................................................2

WhatisUEFI?.........................................................................................................................................................2

WhatUEFIhastoOffer..........................................................................................................................................3

HowisDell’sUEFIimplemented?..........................................................................................................................3

DifferencesbetweenBIOSandUEFIBootModes...........................................................................................4

UEFIBootOptions...........................................................................................................................................4

AutomaticandManualBootOptions....................................................................................................................4

BootingtoaRemovableMediaDevice..................................................................................................................5

UEFIBootManager.........................................................................................................................................5

BootOptions..........................................................................................................................................................5

UEFIBootSettings.................................................................................................................................................5

SystemUtilities......................................................................................................................................................6

DeployingaUEFI‐AwareOperatingSystem....................................................................................................7

DeployingaUEFIOperatingSystem......................................................................................................................7

Limitations.......................................................................................................................................................8

LargeOperatingSystemPartitions........................................................................................................................8

ThirdPartyImagingUtilities..................................................................................................................................8

TransferringHardDisks.........................................................................................................................................8

UEFILegacyBootControllers.................................................................................................................................8

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History

Inthemid‐1990sduringthedevelopmentofIntel’sItanium‐basedsystem,PCBIOSlimitations(forexample,16‐bit

processormode,1MBaddressablespace,PCAThardwaredependencies,etc.)hinderedplatformdevelopmentfor

Itanium.WhiletheItaniumchipwasnotwellreceived,thedevelopmentexposedsignificantlimitationstothe

originalPCfirmwarearchitecturethatledtothedevelopmentofanewframework,calledExtensibleFirmware

Interface(EFI).

In2005,severalleadingtechcompaniescametogethertocreatetheEFIForum.BasedonEFIarchitecture,the

UEFIForum’smissionwastocreatethefirsteverindustrystandardfirmwareinterfacespecification–Unified

ExtensibleFirmwareInterface(UEFI).DellisrepresentedontheboardofdirectorsoftheUEFIForum.

WhatisUEFI?

TheUEFIspecificationdefinesaninterfacebetweenoperatingsystemsandplatformfirmware.Theinterface

consistsofdatatablesthatcontainplatform‐relatedinformation,plusbootandruntimeservicecallsthatare

availabletotheoperatingsystemanditsloader.

Together,theseprovideastandard,modern

environmentforbootinganoperatingsystemand

runningpre‐bootapplications.

Inadditiontotheservices,UEFIdefinesvarious

protocols/APIstoaccessvarioushardwareandthe

bootdevicesinthesystem.TheUEFIspecificationalso

definesadrivermodelthatisgenericandcanbe

adaptedtoanytypeofbusordevice.TheUEFIDriver

Model

isdesignedtosupporttheexecutionof

modularpiecesofcode,knownasdrivers,thatrunin

theprebootenvironment.Thesedriversmaymanage

orcontrolhardwarebusesanddevicesonthe

platform,ortheymayprovidesomesoftware‐derived,

platform‐specificservice.

Thereare3typesofentitiesthatcan

executeunderUEFIenvironment:

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Applications:SomeexamplesofcommonEFIapplicationsincludetheEFIshell,EFIshell

commands,flashutilities,anddiagnosticutilities.ItisperfectlyacceptabletoinvokeEFI

applicationsfrominsideotherEFIapplications.

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OperatingSystemLoader:AspecialtypeofEFIapplication,calledan

operatingsystemboot

loader,providesthenecessaryinitializationroutinesuntiltheloaderhassetupenoughofthe

operatingsysteminfrastructuretobereadytoassumeownershipofthesystemresources.Once

theoperatingsystemassumescontrol,theEFIcorefreesallofitsboottimeservicesanddrivers,

leaving

onlytherun‐timeservicesanddrivers.

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Drivers:EFIdriversdifferfromEFIapplicationsinthatthedriverstaysresidentinmemoryunless

anerrorisreturnedfromthedriver'sentrypoint.TheEFIcorefirmware,thebootmanager,or

otherEFIapplicationsmayloaddrivers.

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WhatUEFIhastoOffer

TheprimarygoalofUEFIistodefineanarchitecturethatcanscalewithtimeandtoofferstructuredcoding

environmentallowingeasyenablementofnewtechnology.ThemaincharacteristicsofUEFIare:

AbstractionfortheOperation System.TheUEFIspecificationprovidesaninterfacebetweentheplatform

firmwareandthe

operatingsystem.Theinterfaces/API/protocolsmarkaclearboundarybetweenthe

firmwareandtheoperatingsystemandtheoperatingsystemloader.

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Abstractionfordevicesandrelatedcode.UEFIabstractsinterfacesthatmakeitpossibletobuildcode

whichworksonarangeofunderlyinghardwaredeviceswithouthavingexplicitknowledge

ofthespecifics

foreachdevice.Thespecificationdefinesinterfacestoplatformcapabilitiessuchasstandardbustypes

(PCI,USB,andSCSI).Thelistofsupportedbustypesmaygrowovertime.Thesedefinedinterfacesandthe

abilitytoextendtofuturebustypesarecomponentsoftheUEFIDriver

Model.



Scalableplatformenvironment.Thespecificationdefinesacompletesolutionforthefirmwareto

describeallplatformfeaturesandcapabilitiestotheoperatingsystemduringthebootprocess.These

definitionscoverarangeofthecontemporaryplatformdesignsbutaresimpleenoughtobeableto

extendinthe

future.



OperatingSystemAgnosticRichPre‐Bootenvironment.TheUEFIspecificationdefinesextensible

interfacesthatenablecreationofplatformdrivers.Thedrivers,analogoustooperatingsystemdrivers,

providesupportfornewdevicesandmayprovideenhancedplatformcapabilities,suchasfirmware

update,platformconfiguration,diagnosticsanddeployment services.The

existenceofnetworking,USB,

andfilesystemcapabilitiesaddstotherichnessofthepre‐bootenvironment.



GUIDPartitionTable.TheUEFIdefinesanewstandardlayoutforthepartitiontable,knownasGUID

PartitionTable(GPT).GPTprovidesamoreflexiblemechanismforpartitioningdisksthanthe

Master

BootRecord(MBR)partitioningschemethathasbeencommontocomputers.MBRdiskssupportonly

fourpartitiontableentriesandthepartitionsizeislimitedto2TB.GPTschemeallowsupto128primary

partitionsandcansupportlargerthan2‐terabytepartitions.Somenear‐termlimitationsto2terabyte



supportexistduetodevicesupport,butoncedevicesfullysupportGPT/UEFI,thiswillnolongerbean

issue.Seethe“Limitations”section.

HowisDell’sUEFIimplemented?

TosupportbootingtobothUEFIandnon‐UEFIawareoperatingsystems,theDellBIOSsupportsaBootMode

optionintheBIOSSetupUtility.TheBootModecanbesettoBIOSorUEFI.

SettingtheBootModetoUEFIallowsbootingtoaUEFI‐awareoperatingsystemandprovides

theUEFIBoot

Manager.ThisistheonlychangerequiredtoenableUEFIonthesystem.SettingtheBootModetoBIOSprovides

supportforallcurrentandlegacyoperationsystems.

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DifferencesbetweenBIOSandUEFIBootModes

Thefollowingtablehighlightsthedifferencesbetweenthebootmodes.

Feature

BootMode

BIOS UEFI

OperatingSystemSupport Compatiblewithoperatingsystems

thatdonotsupportUEFI.Allthe

currentandlegacyoperation

systemscanbeinstalledinthis

bootmode.

MustsupportUEFI

BIOSPOST<F11>Boot

ManagerHotKey

EntersBIOSBootManager EntersUEFIBootManager

BootOrderControl ViaBIOSSetupUtility ViaUEFIBootManager

USBEmulation SupportedviaBIOSSetupUtility Notneeded

DefaultBootOrder TraditionalDellBIOSdefaultboot

order

None

BootOptions LegacyBIOSbootstoadrive.

Supportformulti‐bootdrive

requiresabootloader.

InUEFImode,thereisaconceptofa

bootfile.Thisallowsmultiplefiles

tobeaddedasabootoptionona

singledrive.



UEFIBootOptions

ThewaybootoptionsworkinUEFImodediffersfromthatofthelegacyBIOS.TheUEFIbootoption:

Specifiesafileonadriveasaboottarget(vs.adriveasinlegacyBIOS).

Isautomaticallycreatedbytheoperatingsystemduringinstallationandpointstoits

bootfile.

Providesapredeterminedbootpathforremovablemedia.

CanbemanuallyaddedbytheuserviatheUEFIBootManager.

Pointstoaspecificbootfile;henceasystemformatisnotnecessarytomakeadevicebootable.

AutomaticandManualBootOptions

InUEFI

mode,bootoptionsareautomaticallyaddedforremovabledevices.Theseautomaticallyaddedboot

optionscannotbedeleted.OperatingSysteminstallationautomaticallyaddsabootoptionthatpointstothe

OperatingSystemBootloader.BootoptionscanalsobeaddedmanuallybyusingtheUEFIBootManager.Whether

optionsareaddedmanually

orbytheoperatingsystem,theycanbedeletedusingUEFIBootManager.

Multiplebootoptionsperdevice,orperfile,areallowed.Youmaywanttohavetwobootoptionsforthesame

filewithdifferentinputparameters,suchasadebugparameter.WheninstallingaUEFI‐awareoperating

system,

theinstallationprocesswilladdacorrespondingbootoption.

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

BootingtoaRemovableMediaDevice

Tomakearemovabledevicebootable,theUEFIapplicationsimplyneedstoberenamedtoBOOTx64.EFI(case

insensitive)andplacedinthe\EFI\BOOTdirectory.

Whenaremovabledevice,suchasaUSBkey,isdetectedinUEFIBootMode,abootoption

isautomaticallyadded

topointtothefollowinglocation:

\EFI\BOOT\BOOTx64.EFI

UEFIBootManager

TheUEFIBootManagerisenteredbypressing<F11>duringthepre‐bootphaseofsystemstartup.InUEFIboot

mode,itreplacesboththeBIOSBootManagerandthebootconfigurationoptionsintheBIOSSetupUtility<F2>.

WhentheBootModeissettoUEFItheBIOSSetupUtility

fields,BootSequenceandUSBFlashDriveEmulation

Typearegrayedout,replacedbyenhancedoptionsintheUEFIBootManager.

BootOptions

ThefrontpageoftheUEFIBootManagerlistsbootoptionsinorderofbootpriority.Selectionofanyofthese

optionsresultsinanattemptto

boot.Iftheoptionisnotbootable(forexample,nomediainanopticaldrive),an

errormessagedisplaysalongwithaprompttoentertheUEFIBootManagerortheBIOSSetupUtility.

Incaseswhereabootoptionhasbeenaddedmanuallyorbyanoperatingsysteminstallationand

thatoptionisno

longervalid(forexample,ahard‐diskdrivehasbeenremoved),theoption willcontinuetobelisted,butwillbe

grayedoutanddisplay“Unavailable.”BootOptionentriesforremovabledevicesareautomaticallyaddedand

removedbasedininsertionandremovalofthedevice.

UEFIBootSettings

TheUEFIBootSettingsmenucanbeenteredfromthefrontpage.Thefollowingoptionsareavailablefromthis

menu:

Option Description

AddBootOption Providesamenufromwhichtoselectabootoption.

FormassstoragedeviceswithaFAT32filesystem,amenu

displaystonavigatetoafiletoselectasthebootoption.

ForPXE‐capabledevices,thedeviceitselfcanbeselected.



Whenaddinganewbootoption,theDescriptionandOptionalDatacan

beentered.TheDescriptionidentifiesthedeviceintheUEFIBoot

Manager;theOptionalDataispassedtothebootimage,pertheUEFI

specification.

DeleteBootOption Providesamenuofbootoptionsthatweremanuallyandoperating

systeminstalledandcanbedeleted.Bootoptionsthatwere

automaticallyaddedarenotlisted.

Enable/DisableBoot Providesamenuofbootoptionsthatcanbedisabledwhichremoves

themfromthebootoptionlist.Disableddevicescanbere‐enabledfrom

 Page6



Option thismenu.

ChangeBootOrder Allowsthebootpriorityofthebootoptionstobemodified.

One‐TimeBootFromFile ProvidesamenusimilartothatofAddBootOption,butdoesnotaddthe

bootoption.Instead,itattemptstoboottotheselectedfileordevice.

SystemUtilities

TheSystemUtilitiesmenucanbeenteredfromthefrontpage.Thefollowingoptionsareavailablefromthis

menu:

Option Description

SystemSetup EnterstheSystemSetupUtility.Thiscanalsobeenteredbypressing<F2>

duringthepre‐bootphaseofsystemstartup.

SystemServices EntersSystemServices.Thiscanalsobeenteredbypressing<F10>

duringthepre‐bootphaseofsystemstartup.

BIOSBootManager EnterstheBIOSBootManagertoprovidetheabilitytoboottoanon‐UEFI

awareoperatingsystemwhiletheBootModeissettoUEFI.Thisisthe

sameBootManagerthatwouldbeenteredbypressing<F11>duringthe

pre‐bootphaseofsystemstartup

iftheBootModeissettoBIOS.

RebootSystem Rebootssystem.

 Page7



DeployingaUEFI‐AwareOperatingSystem

OncethehardwareandfirmwaresupportUEFI,theoperatingsystemneedstoberedesignedtosupportUEFI.

UEFIisstillanemergingtechnologyandstandard,sothereareonlyafewoperatingsystemsthathavefullsupport.

DelloffersbothlegacyBIOS‐modeandUEFI‐mode.

OperatingSystemsthatsupportUEFI

‐

1) Microsoft®Windows®Vista,SP1andWindowsServer®2008–X64versionsonly.

2) SUSE

LinuxEnterpriseServer,release11,willcontainsupport

3) GeneralLinuxsupportisavailable,butaskyouroperatingsystemvendoriftheyfullysupportUEFIorwhat

theirplansare.

DeployingaUEFIOperatingSystem

ForMicrosoftoperatingsystems,press<F11>andchangetheBootManagertoUEFI.Oncethisisdone,simply

bootfromtheWindowsServer2008orVistaDVDandfollowthenormalinstallationsteps.Fromthisperspective,

everythingwillbethesameasBIOS‐modeinstallation.

WhatHASchanged?–

The

primaryvisiblechangesaretotheharddrivesetupalthoughthisisnotvisibletothecustomerduring

installation.BIOS‐modesetupinstallsMBRandhasasinglebootpartition.UEFIusesGPT.ForaMicrosoft

Windowsinstallation,threepartitionsarecreated:

Partition Type Format

EFISystemPartition(ESP) EFI(hidden) FAT32

MicrosoftReservedPartition(MSR) MSR

Windowsoperatingsystempartition Primary NTFS



TheESPcontainstheEFI‐capableWindowsBootManager,bootconfigurationdata(BCD),andrelatedfontfiles

TheMSRisusedtostoremetadataoutsideoftheWindowsvolume.TheMSRpartitionmustexistbetweenthe

ESPandtheWindowsoperatingsystempartitions.

Thesepartitionsarevisible

withtheDiskpartutility–DONOTchangeorremovethesepartitions.



IMPORTANT:YoucannotswitchbetweenBIOS‐modeandUEFI‐modewithoutfullywipingthedrive,eitherby

usingtheDiskpartCleancommandorthroughtheharddiskcontrollerandreinitializingtheharddrive.Onceyou

transitiontoUEFI,

DellrecommendsthatyouleavethesysteminUEFI‐mode.

Oncetheoperatingsystemisinstalled,youcaninstallapplicationsandusethesystemnormallywithafewcaveats.

Thereareapplicationsthatmaytrytointeractwiththeharddrivedirectly(imagingtools)–thesemaynotworkas

 Page8



expected.Dellrecommendsthatyoucontactyourapplicationvendorsforallmission‐criticalapplicationsto

ensuretheyworkintheUEFIenvironment.

Limitations

ThissectionexplainspotentialproblemswhichmayoccurwhileinstallingaUEFI‐awareoperatingsystemandhow

toavoidthem.

LargeOperatingSystemPartitions

Anoperatingsysteminstallerreliesondiskcontrollerfirmwaretoperformdiskread/writefunctionspriortothe

diskdriverisavailable.Certainlegacydiskcontrollersuseolder

firmware(suchasInterrupt0x13handlers)to

executeread/writefunctionsinUEFImodeanddonotprovidenativeaccessdisksinUEFImode.TheUEFIlayer

providestheabstractiondrivertoaccessthedisksusingtheoldfirmware.Themostnotablerestrictionisthatthe

legacyinterrupt0x13functionsare

unabletoaccesslogicalblockaddresseshigherthan2terabytes(TB).Forthis

reason,Dellstronglyrecommendsusingapartitionorvirtualdisksmallerthan2TBforthepartitionwherethe

operatingsystemresides.Failuretouseapartitionsizeoflessthan2TBfortheoperatingsystemvirtualdiskmay



causeundesiredbehaviorandwilleliminatetheinherentGPTpartitionredundancy.Datapartitions(non‐system

partitions)canbelargerthan 2TBsincethediskdriverisavailablewhentheoperatingsystemaccessesthese

partitions.

ThirdPartyImagingUtilities

UEFIusesapartitioningschemeknownasaGPT.Thisschemeassigns

aGloballyUniqueIdentifier(GUID)toeach

partitioninadisk.Beawarethatimagingutilities(suchasNortonGhost)needtore‐createtheGPTinorderto

haveuniqueGUIDsforpartitionswhicharecopiedfromonedisktoanother.Otherwisedifferentdiskswillusethe

sameGUIDfor

multiplepartitions,whichmaycauseconflictsforsoftwarewhichusestheGUIDstodistinguisheach

partition.

TransferringHardDisks

UEFIBootOptionsarestoredinnon‐volatilememoryonasystem.Whenanoperatingsysteminstallerexecutes,it

createsabootoptionfortheoperatingsysteminthesystem’snon‐

volatilememory.Iftheharddiskwhich

containstheoperatingsystemisremovedandtransferredtoanothersystem,thisnewsystemwillnothavethe

bootoptioninitsnon‐volatilememory,andauserwillnotbeabletoboottotheoperatingsystem.

Dellhasaddressedthisproblemby

keepingacopyoftheoperatingsystembootoptionontheharddiskwiththe

operatingsystem.WhentheharddiskistransferredtoanotherDellsystem,thesystemusesthecopyofthe

operatingsystembootoptiontocreateabootoptioninitsnon‐volatilememory.Thisallows

ausertoboottothe

operatingsystem.Theprocessisautomatic;nouserinteractionisnecessarytocreatethebootoptiononthe

secondsystem.

UEFILegacyBootControllers

TheUEFIlayerprovidestheabstractiondrivertoaccessthedisksusingtheinterrupt0x13functions.Thefollowing

DellUEFILegacybootcontrollersoperateusinglegacyabstractionsupportedinUEFImode:

DellPERC6/i

DellSAS6/iR

FuturecontrollerswillprovidenativeUEFIdrivers.



Dell PowerEdge T710, PowerEdge R410 Owner's manual

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