€•;      Œsphinx.addnodes”Œdocument”“”)”}”(Œ	rawsource”Œ ”Œchildren”]”(Œtranslations”ŒLanguagesNode”“”)”}”(hhh]”(h Œpending_xref”“”)”}”(hhh]”Œdocutils.nodes”ŒText”“”ŒChinese (Simplified)”…””}”(hhŒparent”hubaŒ
attributes”}”(Œids”]”Œclasses”]”Œnames”]”Œdupnames”]”Œbackrefs”]”Œ	refdomain”Œstd”Œreftype”Œdoc”Œ	reftarget”Œ(/translations/zh_CN/admin-guide/efi-stub”Œmodname”NŒ	classname”NŒrefexplicit”ˆuŒtagname”hhhubh)”}”(hhh]”hŒChinese (Traditional)”…””}”(hhhh2ubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/zh_TW/admin-guide/efi-stub”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒItalian”…””}”(hhhhFubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/it_IT/admin-guide/efi-stub”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒJapanese”…””}”(hhhhZubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/ja_JP/admin-guide/efi-stub”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒKorean”…””}”(hhhhnubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/ko_KR/admin-guide/efi-stub”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubh)”}”(hhh]”hŒSpanish”…””}”(hhhh‚ubah}”(h]”h ]”h"]”h$]”h&]”Œ	refdomain”h)Œreftype”h+Œ	reftarget”Œ(/translations/sp_SP/admin-guide/efi-stub”Œmodname”NŒ	classname”NŒrefexplicit”ˆuh1hhhubeh}”(h]”h ]”h"]”h$]”h&]”Œcurrent_language”ŒEnglish”uh1h
hhŒ	_document”hŒsource”NŒline”NubhŒsection”“”)”}”(hhh]”(hŒtitle”“”)”}”(hŒThe EFI Boot Stub”h]”hŒThe EFI Boot Stub”…””}”(hhªhh¨hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hh£hžhhŸŒB/var/lib/git/docbuild/linux/Documentation/admin-guide/efi-stub.rst”h KubhŒ	paragraph”“”)”}”(hXv  On the x86 and ARM platforms, a kernel zImage/bzImage can masquerade
as a PE/COFF image, thereby convincing EFI firmware loaders to load
it as an EFI executable. The code that modifies the bzImage header,
along with the EFI-specific entry point that the firmware loader
jumps to are collectively known as the "EFI boot stub", and live in
arch/x86/boot/header.S and drivers/firmware/efi/libstub/x86-stub.c,
respectively. For ARM the EFI stub is implemented in
arch/arm/boot/compressed/efi-header.S and
drivers/firmware/efi/libstub/arm32-stub.c. EFI stub code that is shared
between architectures is in drivers/firmware/efi/libstub.”h]”hXz  On the x86 and ARM platforms, a kernel zImage/bzImage can masquerade
as a PE/COFF image, thereby convincing EFI firmware loaders to load
it as an EFI executable. The code that modifies the bzImage header,
along with the EFI-specific entry point that the firmware loader
jumps to are collectively known as the â€œEFI boot stubâ€, and live in
arch/x86/boot/header.S and drivers/firmware/efi/libstub/x86-stub.c,
respectively. For ARM the EFI stub is implemented in
arch/arm/boot/compressed/efi-header.S and
drivers/firmware/efi/libstub/arm32-stub.c. EFI stub code that is shared
between architectures is in drivers/firmware/efi/libstub.”…””}”(hh»hh¹hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hX   For arm64, there is no compressed kernel support, so the Image itself
masquerades as a PE/COFF image and the EFI stub is linked into the
kernel. The arm64 EFI stub lives in drivers/firmware/efi/libstub/arm64.c
and drivers/firmware/efi/libstub/arm64-stub.c.”h]”hX   For arm64, there is no compressed kernel support, so the Image itself
masquerades as a PE/COFF image and the EFI stub is linked into the
kernel. The arm64 EFI stub lives in drivers/firmware/efi/libstub/arm64.c
and drivers/firmware/efi/libstub/arm64-stub.c.”…””}”(hhÉhhÇhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hŒñBy using the EFI boot stub it's possible to boot a Linux kernel
without the use of a conventional EFI boot loader, such as grub or
elilo. Since the EFI boot stub performs the jobs of a boot loader, in
a certain sense it *IS* the boot loader.”h]”(hŒÞBy using the EFI boot stub itâ€™s possible to boot a Linux kernel
without the use of a conventional EFI boot loader, such as grub or
elilo. Since the EFI boot stub performs the jobs of a boot loader, in
a certain sense it ”…””}”(hŒÜBy using the EFI boot stub it's possible to boot a Linux kernel
without the use of a conventional EFI boot loader, such as grub or
elilo. Since the EFI boot stub performs the jobs of a boot loader, in
a certain sense it ”hhÕhžhhŸNh NubhŒemphasis”“”)”}”(hŒ*IS*”h]”hŒIS”…””}”(hhhhàhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1hÞhhÕubhŒ the boot loader.”…””}”(hŒ the boot loader.”hhÕhžhhŸNh Nubeh}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¸)”}”(hŒDThe EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option.”h]”hŒDThe EFI boot stub is enabled with the CONFIG_EFI_STUB kernel option.”…””}”(hhûhhùhžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Khh£hžhubh¢)”}”(hhh]”(h§)”}”(hŒHow to install bzImage.efi”h]”hŒHow to install bzImage.efi”…””}”(hj  hj
  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hj  hžhhŸh¶h Kubh¸)”}”(hX  The bzImage located in arch/x86/boot/bzImage must be copied to the EFI
System Partition (ESP) and renamed with the extension ".efi". Without
the extension the EFI firmware loader will refuse to execute it. It's
not possible to execute bzImage.efi from the usual Linux file systems
because EFI firmware doesn't have support for them. For ARM the
arch/arm/boot/zImage should be copied to the system partition, and it
may not need to be renamed. Similarly for arm64, arch/arm64/boot/Image
should be copied but not necessarily renamed.”h]”hX  The bzImage located in arch/x86/boot/bzImage must be copied to the EFI
System Partition (ESP) and renamed with the extension â€œ.efiâ€. Without
the extension the EFI firmware loader will refuse to execute it. Itâ€™s
not possible to execute bzImage.efi from the usual Linux file systems
because EFI firmware doesnâ€™t have support for them. For ARM the
arch/arm/boot/zImage should be copied to the system partition, and it
may not need to be renamed. Similarly for arm64, arch/arm64/boot/Image
should be copied but not necessarily renamed.”…””}”(hj  hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K hj  hžhubeh}”(h]”Œhow-to-install-bzimage-efi”ah ]”h"]”Œhow to install bzimage.efi”ah$]”h&]”uh1h¡hh£hžhhŸh¶h Kubh¢)”}”(hhh]”(h§)”}”(hŒ,Passing kernel parameters from the EFI shell”h]”hŒ,Passing kernel parameters from the EFI shell”…””}”(hj3  hj1  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hj.  hžhhŸh¶h K+ubh¸)”}”(hŒ?Arguments to the kernel can be passed after bzImage.efi, e.g.::”h]”hŒ>Arguments to the kernel can be passed after bzImage.efi, e.g.:”…””}”(hŒ>Arguments to the kernel can be passed after bzImage.efi, e.g.:”hj?  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K-hj.  hžhubhŒliteral_block”“”)”}”(hŒ.fs0:> bzImage.efi console=ttyS0 root=/dev/sda4”h]”hŒ.fs0:> bzImage.efi console=ttyS0 root=/dev/sda4”…””}”(hhhjP  ubah}”(h]”h ]”h"]”h$]”h&]”Œ	xml:space”Œpreserve”uh1jN  hŸh¶h K/hj.  hžhubeh}”(h]”Œ,passing-kernel-parameters-from-the-efi-shell”ah ]”h"]”Œ,passing kernel parameters from the efi shell”ah$]”h&]”uh1h¡hh£hžhhŸh¶h K+ubh¢)”}”(hhh]”(h§)”}”(hŒThe "initrd=" option”h]”hŒThe â€œinitrd=â€ option”…””}”(hjm  hjk  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hjh  hžhhŸh¶h K3ubh¸)”}”(hŒãLike most boot loaders, the EFI stub allows the user to specify
multiple initrd files using the "initrd=" option. This is the only EFI
stub-specific command line parameter, everything else is passed to the
kernel when it boots.”h]”hŒçLike most boot loaders, the EFI stub allows the user to specify
multiple initrd files using the â€œinitrd=â€ option. This is the only EFI
stub-specific command line parameter, everything else is passed to the
kernel when it boots.”…””}”(hj{  hjy  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K5hjh  hžhubh¸)”}”(hX  The path to the initrd file must be an absolute path from the
beginning of the ESP, relative path names do not work. Also, the path
is an EFI-style path and directory elements must be separated with
backslashes (\). For example, given the following directory layout::”h]”hX
  The path to the initrd file must be an absolute path from the
beginning of the ESP, relative path names do not work. Also, the path
is an EFI-style path and directory elements must be separated with
backslashes ( ). For example, given the following directory layout:”…””}”(hX
  The path to the initrd file must be an absolute path from the
beginning of the ESP, relative path names do not work. Also, the path
is an EFI-style path and directory elements must be separated with
backslashes (\). For example, given the following directory layout:”hj‡  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K:hjh  hžhubjO  )”}”(hŒ½fs0:>
      Kernels\
                      bzImage.efi
                      initrd-large.img

      Ramdisks\
                      initrd-small.img
                      initrd-medium.img”h]”hŒ½fs0:>
      Kernels\
                      bzImage.efi
                      initrd-large.img

      Ramdisks\
                      initrd-small.img
                      initrd-medium.img”…””}”(hhhj–  ubah}”(h]”h ]”h"]”h$]”h&]”j^  j_  uh1jN  hŸh¶h K?hjh  hžhubh¸)”}”(hŒ}to boot with the initrd-large.img file if the current working
directory is fs0:\Kernels, the following command must be used::”h]”hŒ|to boot with the initrd-large.img file if the current working
directory is fs0: Kernels, the following command must be used:”…””}”(hŒ|to boot with the initrd-large.img file if the current working
directory is fs0:\Kernels, the following command must be used:”hj¤  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KHhjh  hžhubjO  )”}”(hŒ:fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img”h]”hŒ:fs0:\Kernels> bzImage.efi initrd=\Kernels\initrd-large.img”…””}”(hhhj³  ubah}”(h]”h ]”h"]”h$]”h&]”j^  j_  uh1jN  hŸh¶h KKhjh  hžhubh¸)”}”(hŒèNotice how bzImage.efi can be specified with a relative path. That's
because the image we're executing is interpreted by the EFI shell,
which understands relative paths, whereas the rest of the command line
is passed to bzImage.efi.”h]”hŒìNotice how bzImage.efi can be specified with a relative path. Thatâ€™s
because the image weâ€™re executing is interpreted by the EFI shell,
which understands relative paths, whereas the rest of the command line
is passed to bzImage.efi.”…””}”(hjÃ  hjÁ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KMhjh  hžhubeh}”(h]”Œthe-initrd-option”ah ]”h"]”Œthe "initrd=" option”ah$]”h&]”uh1h¡hh£hžhhŸh¶h K3ubh¢)”}”(hhh]”(h§)”}”(hŒThe "dtb=" option”h]”hŒThe â€œdtb=â€ option”…””}”(hjÜ  hjÚ  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h¦hj×  hžhhŸh¶h KTubh¸)”}”(hX2  For the ARM and arm64 architectures, a device tree must be provided to
the kernel. Normally firmware shall supply the device tree via the
EFI CONFIGURATION TABLE. However, the "dtb=" command line option can
be used to override the firmware supplied device tree, or to supply
one when firmware is unable to.”h]”hX6  For the ARM and arm64 architectures, a device tree must be provided to
the kernel. Normally firmware shall supply the device tree via the
EFI CONFIGURATION TABLE. However, the â€œdtb=â€ command line option can
be used to override the firmware supplied device tree, or to supply
one when firmware is unable to.”…””}”(hjê  hjè  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h KVhj×  hžhubh¸)”}”(hXc  Please note: Firmware adds runtime configuration information to the
device tree before booting the kernel. If dtb= is used to override
the device tree, then any runtime data provided by firmware will be
lost. The dtb= option should only be used either as a debug tool, or
as a last resort when a device tree is not provided in the EFI
CONFIGURATION TABLE.”h]”hXc  Please note: Firmware adds runtime configuration information to the
device tree before booting the kernel. If dtb= is used to override
the device tree, then any runtime data provided by firmware will be
lost. The dtb= option should only be used either as a debug tool, or
as a last resort when a device tree is not provided in the EFI
CONFIGURATION TABLE.”…””}”(hjø  hjö  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h K\hj×  hžhubh¸)”}”(hŒW"dtb=" is processed in the same manner as the "initrd=" option that is
described above.”h]”hŒ_â€œdtb=â€ is processed in the same manner as the â€œinitrd=â€ option that is
described above.”…””}”(hj  hj  hžhhŸNh Nubah}”(h]”h ]”h"]”h$]”h&]”uh1h·hŸh¶h Kchj×  hžhubeh}”(h]”Œthe-dtb-option”ah ]”h"]”Œthe "dtb=" option”ah$]”h&]”uh1h¡hh£hžhhŸh¶h KTubeh}”(h]”Œthe-efi-boot-stub”ah ]”h"]”Œthe efi boot stub”ah$]”h&]”uh1h¡hhhžhhŸh¶h Kubeh}”(h]”h ]”h"]”h$]”h&]”Œsource”h¶uh1hŒcurrent_source”NŒcurrent_line”NŒsettings”Œdocutils.frontend”ŒValues”“”)”}”(h¦NŒ	generator”NŒ	datestamp”NŒsource_link”NŒ
source_url”NŒtoc_backlinks”Œentry”Œfootnote_backlinks”KŒsectnum_xform”KŒstrip_comments”NŒstrip_elements_with_classes”NŒstrip_classes”NŒreport_level”KŒ
halt_level”KŒexit_status_level”KŒdebug”NŒwarning_stream”NŒ	traceback”ˆŒinput_encoding”Œ	utf-8-sig”Œinput_encoding_error_handler”Œstrict”Œoutput_encoding”Œutf-8”Œoutput_encoding_error_handler”jE  Œerror_encoding”ŒUTF-8”Œerror_encoding_error_handler”Œbackslashreplace”Œlanguage_code”Œen”Œrecord_dependencies”NŒconfig”NŒ	id_prefix”hŒauto_id_prefix”Œid”Œdump_settings”NŒdump_internals”NŒdump_transforms”NŒdump_pseudo_xml”NŒexpose_internals”NŒstrict_visitor”NŒ_disable_config”NŒ_source”h¶Œ_destination”NŒ_config_files”]”Œ7/var/lib/git/docbuild/linux/Documentation/docutils.conf”aŒpep_references”NŒpep_base_url”Œhttps://peps.python.org/”Œpep_file_url_template”Œpep-%04d”Œrfc_references”NŒrfc_base_url”Œ&https://datatracker.ietf.org/doc/html/”Œ	tab_width”KŒtrim_footnote_reference_space”‰Œfile_insertion_enabled”ˆŒraw_enabled”KŒline_length_limit”M'Œsyntax_highlight”Œlong”Œsmart_quotes”ˆŒsmartquotes_locales”]”Œcharacter_level_inline_markup”‰Œdoctitle_xform”‰Œdocinfo_xform”KŒsectsubtitle_xform”‰Œimage_loading”Œlink”Œembed_stylesheet”‰Œcloak_email_addresses”ˆŒsection_self_link”‰Œembed_images”‰Œenv”NubŒreporter”NŒindirect_targets”]”Œsubstitution_defs”}”Œsubstitution_names”}”Œrefnames”}”Œrefids”}”Œnameids”}”(j  j  j+  j(  je  jb  jÔ  jÑ  j  j  uŒ	nametypes”}”(j  Nj+  Nje  NjÔ  Nj  Nuh}”(j  h£j(  j  jb  j.  jÑ  jh  j  j×  uŒfootnote_refs”}”Œcitation_refs”}”Œautofootnotes”]”Œautofootnote_refs”]”Œsymbol_footnotes”]”Œsymbol_footnote_refs”]”Œ	footnotes”]”Œ	citations”]”Œautofootnote_start”KŒsymbol_footnote_start”K Œ
id_counter”Œcollections”ŒCounter”“”}”…”R”Œparse_messages”]”Œtransform_messages”]”Œtransformer”NŒinclude_log”]”Œ
decoration”Nhžhub.