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diff --git a/Lesson_32/README.md b/Lesson_32/README.md index 0037a46..bab0b9d 100644 --- a/Lesson_32/README.md +++ b/Lesson_32/README.md @@ -541,341 +541,3 @@ Memory Address 0000000006E59018 C0 Bytes 06E590C8: 0E 1F BE 27 03 31 FF E8-4C 04 8E EB 31 FF E8 3D *...'.1..L...1..=* ``` -# EfiRom - -In the next sections will be investigating OptionROM images with the help of BaseTools utility `EfiRom`. It is available in your path once you'll execute `. edksetup.sh` in edk2 folder. - -First take a look at `EfiRom` help: -``` -$ EfiRom -h -Usage: EfiRom -f VendorId -i DeviceId [options] [file name<s>] - -Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved. - -Options: - -o FileName, --output FileName - File will be created to store the output content. - -e EfiFileName - EFI PE32 image files. - -ec EfiFileName - EFI PE32 image files and will be compressed. - -b BinFileName - Legacy binary files. - -l ClassCode - Hex ClassCode in the PCI data structure header. - -r Rev Hex Revision in the PCI data structure header. - -n Not to automatically set the LAST bit in the last file. - -f VendorId - Hex PCI Vendor ID for the device OpROM, must be specified - -i DeviceId - One or more hex PCI Device IDs for the device OpROM, must be specified - -p, --pci23 - Default layout meets PCI 3.0 specifications - specifying this flag will for a PCI 2.3 layout. - -d, --dump - Dump the headers of an existing option ROM image. - -v, --verbose - Turn on verbose output with informational messages. - --version Show program's version number and exit. - -h, --help - Show this help message and exit. - -q, --quiet - Disable all messages except FATAL ERRORS. - --debug [#,0-9] - Enable debug messages at level #. -``` -Complete version of the manual for `EfiRom` is placed at https://github.com/tianocore/edk2/blob/master/BaseTools/UserManuals/EfiRom_Utility_Man_Page.rtf - -If you are interested in the source code: https://github.com/tianocore/edk2/tree/master/BaseTools/Source/C/EfiRom - -With this tool it is possible to: -- dump Option ROM images -- create Option ROM images from EFI drivers and/or Legacy binary images - -Also take a look at tianocore docs: -- https://edk2-docs.gitbook.io/edk-ii-basetools-user-guides/efirom -- https://edk2-docs.gitbook.io/edk-ii-uefi-driver-writer-s-guide/18_pci_driver_design_guidelines/readme.7/1871_efirom_utility - -# ipxe rom - -Preboot eXecution Environment (PXE) is a standard for booting to an image received via network (https://en.wikipedia.org/wiki/Preboot_Execution_Environment). - -To know how to use particular PCI network card for PXE boot, BIOS needs to know some network card internals. But BIOS is not an OS, it is not possible to have drivers for every PCI network card in it. Therefore this problem is solved via OptionROM firmware. PCI network card contains all the necessary code for PXE boot in itself. But not every card have such firmware in itself. In this case you can utilize iPXE project. - -iPXE is the open source network boot firmware (https://ipxe.org/). It provides a full PXE implementation enhanced with some additional features. It support various PCI network cards https://ipxe.org/appnote/hardware_drivers. - -iPXE can be compiled as EFI application or as EFI/Legacy OptionROM. You can read more about build targets at https://ipxe.org/appnote/buildtargets. - -Let's download iPXE: -``` -git clone git://git.ipxe.org/ipxe.git -cd ipxe/src -``` - -Now build some images: -``` -$ sudo apt-get install liblzma-dev -$ make bin-x86_64-efi/ipxe.efi # EFI app with all devices -$ make bin-x86_64-efi/8086100e.efirom # EFI ROM vendev: 8086:100e -$ make bin/8086100e.rom # Legacy ROM vendev: 8086:100e -``` - -You can execute `ipxe.efi` directly from the UEFI shell. It is a simple UEFI application similar to the ones that we create in this series. - -Look at the https://github.com/ipxe/ipxe/blob/master/src/image/efi_image.c for source code investigation. - -`8086100e.rom` is a Legacy code image PCI Option ROM for `8086:100e` network card - -`8086100e.efirom` is an UEFI code image PCI Option ROM for `8086:100e` network card - -If you inspect the OptionROM images with `hexdump`, you'll see standard `AA55` and `PCIR` signatures in them. - -``` -$ hexdump bin/8086100e.rom -C -n 64 -00000000 55 aa 86 e9 a2 00 30 00 00 00 00 00 00 00 00 00 |U.....0.........| -00000010 9c 00 00 00 00 00 84 00 1c 00 40 00 50 43 49 52 |..........@.PCIR| -00000020 86 80 0e 10 bf 04 1c 00 03 00 00 02 86 00 01 00 |................| -00000030 00 80 07 00 00 00 00 00 8d b4 00 00 8d b4 00 00 |................| -00000040 -$ hexdump bin-x86_64-efi/8086100e.efirom -C -n 64 -00000000 55 aa d0 00 f1 0e 00 00 0b 00 64 86 01 00 00 00 |U.........d.....| -00000010 00 00 00 00 00 00 38 00 1c 00 00 00 50 43 49 52 |......8.....PCIR| -00000020 86 80 0e 10 00 00 18 00 00 00 00 02 d0 00 00 00 |................| -00000030 03 80 00 00 87 00 00 00 0d 9e 01 00 00 d2 02 00 |................| -00000040 -``` - -We can even use `EfiRom` on them: -``` -$ EfiRom -d bin/8086100e.rom -Image 1 -- Offset 0x0 - ROM header contents - Signature 0xAA55 - PCIR offset 0x001C - Signature PCIR - Vendor ID 0x8086 - Device ID 0x100E - Length 0x001C - Revision 0x0003 - DeviceListOffset 0x4BF - Device list contents - 0x100E - Class Code 0x020000 - Image size 0x10C00 - Code revision: 0x0001 - MaxRuntimeImageLength 0x07 - ConfigUtilityCodeHeaderOffset 0x00 - DMTFCLPEntryPointOffset 0x00 - Indicator 0x80 (last image) - Code type 0x00 -``` -If we execute `EfiRom` on a `bin-x86_64-efi/8086100e.efirom`, we would get an error: -``` -$ EfiRom -d bin-x86_64-efi/8086100e.efirom -EfiRom: ERROR 1002: No PciRom input file - No *.rom input file -``` -The problem is that we `EfiRom` understands only files with `.rom` extension, so change it and use `EfiRom` again: -``` -$ cp bin-x86_64-efi/8086100e.efirom bin-x86_64-efi/8086100e.rom -$ EfiRom -d bin-x86_64-efi/8086100e.rom -Image 1 -- Offset 0x0 - ROM header contents - Signature 0xAA55 - PCIR offset 0x001C - Signature PCIR - Vendor ID 0x8086 - Device ID 0x100E - Length 0x0018 - Revision 0x0000 - DeviceListOffset 0x00 - Class Code 0x020000 - Image size 0x1A000 - Code revision: 0x0000 - MaxRuntimeImageLength 0x00 - ConfigUtilityCodeHeaderOffset 0x87 - DMTFCLPEntryPointOffset 0x00 - Indicator 0x80 (last image) - Code type 0x03 (EFI image) - EFI ROM header contents - EFI Signature 0x0EF1 - Compression Type 0x0001 (compressed) - Machine type 0x8664 (X64) - Subsystem 0x000B (EFI boot service driver) - EFI image offset 0x0038 (@0x38) -``` - -EfiRom can't currently combine Option ROM from the EFI ROM images. But it can use EFI PE32 image files as a source for EFI ROM images in the resulting Option ROM. So we have to compile another target: -``` -$ make bin-x86_64-efi/8086100e.efidrv -``` -Now we can create combined OptionROM image with both Legacy and EFI ROMs. -``` -$ EfiRom -f 0x8086 -i 0x100e -b bin/8086100e.rom -ec bin-x86_64-efi/8086100e.efidrv -o bin/8086100e_optionrom.rom -$ EfiRom -d bin/8086100e_optionrom.rom -Image 1 -- Offset 0x0 - ROM header contents - Signature 0xAA55 - PCIR offset 0x001C - Signature PCIR - Vendor ID 0x8086 - Device ID 0x100E - Length 0x001C - Revision 0x0003 - DeviceListOffset 0x4BF - Device list contents - 0x100E - Class Code 0x020000 - Image size 0x10C00 - Code revision: 0x0001 - MaxRuntimeImageLength 0x07 - ConfigUtilityCodeHeaderOffset 0x00 - DMTFCLPEntryPointOffset 0x00 - Indicator 0x00 - Code type 0x00 -Image 2 -- Offset 0x10C00 - ROM header contents - Signature 0xAA55 - PCIR offset 0x001C - Signature PCIR - Vendor ID 0x8086 - Device ID 0x100E - Length 0x001C - Revision 0x0003 - DeviceListOffset 0x00 - Class Code 0x000000 - Image size 0x1A000 - Code revision: 0x0000 - MaxRuntimeImageLength 0x00 - ConfigUtilityCodeHeaderOffset 0x00 - DMTFCLPEntryPointOffset 0x00 - Indicator 0x80 (last image) - Code type 0x03 (EFI image) - EFI ROM header contents - EFI Signature 0x0EF1 - Compression Type 0x0001 (compressed) - Machine type 0x8664 (X64) - Subsystem 0x000B (EFI boot service driver) - EFI image offset 0x0038 (@0x10C38) -``` - -# VGA rom - -SeaBIOS is an open-source legacy BIOS implementation that implements the standard BIOS calling interfaces that a typical x86 proprietary BIOS implements (https://github.com/coreboot/seabios). -SeaVGABIOS is a sub-project of the SeaBIOS project - it is an open source implementation of a 16bit X86 VGA BIOS -(https://github.com/coreboot/seabios/blob/master/docs/SeaVGABIOS.md). In other words it builds a Legacy Option ROM for a PCI graphic device. - -SeaBIOS uses Kconfig system for the build configuration. Main options for the VGA BIOS are placed under https://github.com/coreboot/seabios/blob/master/vgasrc/Kconfig In this file you can see that one of the options is a OptionROM with a Vendor/Device pair as `1234:1111`. Exactly the one that we saw at QEMU: -``` - config VGA_VID - depends on VGA_PCI - hex - prompt "PCI Vendor ID" if OVERRIDE_PCI_ID - default 0x1013 if VGA_CIRRUS - default 0x1002 if VGA_ATI - default 0x1234 if VGA_BOCHS_STDVGA - default 0x15ad if VGA_BOCHS_VMWARE - default 0x1b36 if VGA_BOCHS_QXL - default 0x1af4 if VGA_BOCHS_VIRTIO - default 0x100b if VGA_GEODEGX2 - default 0x1022 if VGA_GEODELX - default 0x1234 if DISPLAY_BOCHS <-------------- - default 0x0000 - help - Vendor ID for the PCI ROM - - config VGA_DID - depends on VGA_PCI - hex - prompt "PCI Vendor ID" if OVERRIDE_PCI_ID - default 0x00b8 if VGA_CIRRUS - default 0x5159 if VGA_ATI - default 0x1111 if VGA_BOCHS_STDVGA - default 0x0405 if VGA_BOCHS_VMWARE - default 0x0100 if VGA_BOCHS_QXL - default 0x1050 if VGA_BOCHS_VIRTIO - default 0x0030 if VGA_GEODEGX2 - default 0x2081 if VGA_GEODELX - default 0x1111 if DISPLAY_BOCHS <--------------- - default 0x0000 - help - Device ID for the PCI ROM -``` -If you wonder what is `DISPLAY_BOCHS`, here is a help for this option: -``` - config DISPLAY_BOCHS - depends on QEMU - bool "qemu bochs-display support" - select VGA_EMULATE_TEXT - help - Build support for the qemu bochs-display device, which - is basically qemu stdvga without the legacy vga - emulation, supporting only 16+32 bpp VESA video modes - in a linear framebuffer. So this uses cbvga text mode - emulation. - - The bochs-display device is available in qemu - v3.0+. The vgabios works with the qemu stdvga too (use - "qemu -device VGA,romfile=/path/to/vgabios.bin")". -``` - -Let's build this SeaBIOS VGA image. Install necessary packages, download SeaBIOS source and perfrorm build configuration: -``` -$ sudo apt-get install python -$ git clone https://github.com/coreboot/seabios.git -$ cd seabios -$ make menuconfig -``` -In a menuconfig select: -``` -VGA ROM ---> VGA Hardware Type (qemu bochs-display support) -``` -After that execute: -``` -$ make -``` - -After the build resulting VGA Option ROM would be at path `out/vgabios.bin`. As `EfiRom` expects ROM files to have a `*.rom` extension, create a copy of a file with such extension. After that execute `dump` command on this file: -``` -$ cp out/vgabios.bin out/vgabios.rom -$ EfiRom -d out/vgabios.rom -Image 1 -- Offset 0x0 - ROM header contents - Signature 0xAA55 - PCIR offset 0x6E00 - Signature PCIR - Vendor ID 0x1234 - Device ID 0x1111 - Length 0x0018 - Revision 0x0000 - DeviceListOffset 0x00 - Class Code 0x030000 - Image size 0x7000 - Code revision: 0x0001 - MaxRuntimeImageLength 0x00 - ConfigUtilityCodeHeaderOffset 0x9066 - DMTFCLPEntryPointOffset 0x9066 - Indicator 0x80 (last image) - Code type 0x00 -``` -This is the info similar to the one that we saw with our utility on a working QEMU system. You can see that PCI vendor/device pair is set to `1234:1111`. - - -# How QEMU gets these OptionROMs - -The main Makefile in QEMU responsible for OptionROM image creation is https://github.com/qemu/qemu/blob/master/roms/Makefile - -In this Makefile you can see how: -- `seavgabios-%` target is used for the creation of a Legacy SeaVGABIOS OptionROM -- `efi-rom-%` target is used for the creation of an OptionROM with both Legacy and UEFI iPXE code images (it even uses `EfiRom` utility from edk2 for this purpose) - -# Code images for different CPU architectures in OptionROM image - -In the intro I've mentioned that PCI device can have various code images for different CPU architectures. - -Check out this guide as an example https://www.workofard.com/2020/12/aarch64-option-roms-for-amd-gpus/ - -It explains how to add the AMD AARCH64 Gop Driver as another Code Image to the PCI graphic card OptionROM to make the graphic card work at boot time in AArch64 systems. - -It uses `flashrom` utility to download initial PCI card Option ROM firmware and with a help of `EfiRom` adds AMD EFI graphic driver for AArch64 to the list of images in this OptionROM. - diff --git a/Lesson_33/README.md b/Lesson_33/README.md new file mode 100644 index 0000000..2f0968a --- /dev/null +++ b/Lesson_33/README.md @@ -0,0 +1,335 @@ +In this lesson we will be investigating OptionROM images with the help of BaseTools utility `EfiRom`. It is available in your path once you'll execute `. edksetup.sh` in edk2 folder. + +First take a look at `EfiRom` help: +``` +$ EfiRom -h +Usage: EfiRom -f VendorId -i DeviceId [options] [file name<s>] + +Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved. + +Options: + -o FileName, --output FileName + File will be created to store the output content. + -e EfiFileName + EFI PE32 image files. + -ec EfiFileName + EFI PE32 image files and will be compressed. + -b BinFileName + Legacy binary files. + -l ClassCode + Hex ClassCode in the PCI data structure header. + -r Rev Hex Revision in the PCI data structure header. + -n Not to automatically set the LAST bit in the last file. + -f VendorId + Hex PCI Vendor ID for the device OpROM, must be specified + -i DeviceId + One or more hex PCI Device IDs for the device OpROM, must be specified + -p, --pci23 + Default layout meets PCI 3.0 specifications + specifying this flag will for a PCI 2.3 layout. + -d, --dump + Dump the headers of an existing option ROM image. + -v, --verbose + Turn on verbose output with informational messages. + --version Show program's version number and exit. + -h, --help + Show this help message and exit. + -q, --quiet + Disable all messages except FATAL ERRORS. + --debug [#,0-9] + Enable debug messages at level #. +``` +Complete version of the manual for `EfiRom` is placed at https://github.com/tianocore/edk2/blob/master/BaseTools/UserManuals/EfiRom_Utility_Man_Page.rtf + +If you are interested in the source code: https://github.com/tianocore/edk2/tree/master/BaseTools/Source/C/EfiRom + +With this tool it is possible to: +- dump Option ROM images +- create Option ROM images from EFI drivers and/or Legacy binary images + +Also take a look at tianocore docs: +- https://edk2-docs.gitbook.io/edk-ii-basetools-user-guides/efirom +- https://edk2-docs.gitbook.io/edk-ii-uefi-driver-writer-s-guide/18_pci_driver_design_guidelines/readme.7/1871_efirom_utility + +# ipxe rom + +Preboot eXecution Environment (PXE) is a standard for booting to an image received via network (https://en.wikipedia.org/wiki/Preboot_Execution_Environment). + +To know how to use particular PCI network card for PXE boot, BIOS needs to know some network card internals. But BIOS is not an OS, it is not possible to have drivers for every PCI network card in it. Therefore this problem is solved via OptionROM firmware. PCI network card contains all the necessary code for PXE boot in itself. But not every card have such firmware in itself. In this case you can utilize iPXE project. + +iPXE is the open source network boot firmware (https://ipxe.org/). It provides a full PXE implementation enhanced with some additional features. It support various PCI network cards https://ipxe.org/appnote/hardware_drivers. + +iPXE can be compiled as EFI application or as EFI/Legacy OptionROM. You can read more about build targets at https://ipxe.org/appnote/buildtargets. + +Let's download iPXE: +``` +git clone git://git.ipxe.org/ipxe.git +cd ipxe/src +``` + +Now build some images: +``` +$ sudo apt-get install liblzma-dev +$ make bin-x86_64-efi/ipxe.efi # EFI app with all devices +$ make bin-x86_64-efi/8086100e.efirom # EFI ROM vendev: 8086:100e +$ make bin/8086100e.rom # Legacy ROM vendev: 8086:100e +``` + +You can execute `ipxe.efi` directly from the UEFI shell. It is a simple UEFI application similar to the ones that we create in this series. + +Look at the https://github.com/ipxe/ipxe/blob/master/src/image/efi_image.c for source code investigation. + +`8086100e.rom` is a Legacy code image PCI Option ROM for `8086:100e` network card + +`8086100e.efirom` is an UEFI code image PCI Option ROM for `8086:100e` network card + +If you inspect the OptionROM images with `hexdump`, you'll see standard `AA55` and `PCIR` signatures in them. + +``` +$ hexdump bin/8086100e.rom -C -n 64 +00000000 55 aa 86 e9 a2 00 30 00 00 00 00 00 00 00 00 00 |U.....0.........| +00000010 9c 00 00 00 00 00 84 00 1c 00 40 00 50 43 49 52 |..........@.PCIR| +00000020 86 80 0e 10 bf 04 1c 00 03 00 00 02 86 00 01 00 |................| +00000030 00 80 07 00 00 00 00 00 8d b4 00 00 8d b4 00 00 |................| +00000040 +$ hexdump bin-x86_64-efi/8086100e.efirom -C -n 64 +00000000 55 aa d0 00 f1 0e 00 00 0b 00 64 86 01 00 00 00 |U.........d.....| +00000010 00 00 00 00 00 00 38 00 1c 00 00 00 50 43 49 52 |......8.....PCIR| +00000020 86 80 0e 10 00 00 18 00 00 00 00 02 d0 00 00 00 |................| +00000030 03 80 00 00 87 00 00 00 0d 9e 01 00 00 d2 02 00 |................| +00000040 +``` + +We can even use `EfiRom` on them: +``` +$ EfiRom -d bin/8086100e.rom +Image 1 -- Offset 0x0 + ROM header contents + Signature 0xAA55 + PCIR offset 0x001C + Signature PCIR + Vendor ID 0x8086 + Device ID 0x100E + Length 0x001C + Revision 0x0003 + DeviceListOffset 0x4BF + Device list contents + 0x100E + Class Code 0x020000 + Image size 0x10C00 + Code revision: 0x0001 + MaxRuntimeImageLength 0x07 + ConfigUtilityCodeHeaderOffset 0x00 + DMTFCLPEntryPointOffset 0x00 + Indicator 0x80 (last image) + Code type 0x00 +``` +If we execute `EfiRom` on a `bin-x86_64-efi/8086100e.efirom`, we would get an error: +``` +$ EfiRom -d bin-x86_64-efi/8086100e.efirom +EfiRom: ERROR 1002: No PciRom input file + No *.rom input file +``` +The problem is that we `EfiRom` understands only files with `.rom` extension, so change it and use `EfiRom` again: +``` +$ cp bin-x86_64-efi/8086100e.efirom bin-x86_64-efi/8086100e.rom +$ EfiRom -d bin-x86_64-efi/8086100e.rom +Image 1 -- Offset 0x0 + ROM header contents + Signature 0xAA55 + PCIR offset 0x001C + Signature PCIR + Vendor ID 0x8086 + Device ID 0x100E + Length 0x0018 + Revision 0x0000 + DeviceListOffset 0x00 + Class Code 0x020000 + Image size 0x1A000 + Code revision: 0x0000 + MaxRuntimeImageLength 0x00 + ConfigUtilityCodeHeaderOffset 0x87 + DMTFCLPEntryPointOffset 0x00 + Indicator 0x80 (last image) + Code type 0x03 (EFI image) + EFI ROM header contents + EFI Signature 0x0EF1 + Compression Type 0x0001 (compressed) + Machine type 0x8664 (X64) + Subsystem 0x000B (EFI boot service driver) + EFI image offset 0x0038 (@0x38) +``` + +EfiRom can't currently combine Option ROM from the EFI ROM images. But it can use EFI PE32 image files as a source for EFI ROM images in the resulting Option ROM. So we have to compile another target: +``` +$ make bin-x86_64-efi/8086100e.efidrv +``` +Now we can create combined OptionROM image with both Legacy and EFI ROMs. +``` +$ EfiRom -f 0x8086 -i 0x100e -b bin/8086100e.rom -ec bin-x86_64-efi/8086100e.efidrv -o bin/8086100e_optionrom.rom +$ EfiRom -d bin/8086100e_optionrom.rom +Image 1 -- Offset 0x0 + ROM header contents + Signature 0xAA55 + PCIR offset 0x001C + Signature PCIR + Vendor ID 0x8086 + Device ID 0x100E + Length 0x001C + Revision 0x0003 + DeviceListOffset 0x4BF + Device list contents + 0x100E + Class Code 0x020000 + Image size 0x10C00 + Code revision: 0x0001 + MaxRuntimeImageLength 0x07 + ConfigUtilityCodeHeaderOffset 0x00 + DMTFCLPEntryPointOffset 0x00 + Indicator 0x00 + Code type 0x00 +Image 2 -- Offset 0x10C00 + ROM header contents + Signature 0xAA55 + PCIR offset 0x001C + Signature PCIR + Vendor ID 0x8086 + Device ID 0x100E + Length 0x001C + Revision 0x0003 + DeviceListOffset 0x00 + Class Code 0x000000 + Image size 0x1A000 + Code revision: 0x0000 + MaxRuntimeImageLength 0x00 + ConfigUtilityCodeHeaderOffset 0x00 + DMTFCLPEntryPointOffset 0x00 + Indicator 0x80 (last image) + Code type 0x03 (EFI image) + EFI ROM header contents + EFI Signature 0x0EF1 + Compression Type 0x0001 (compressed) + Machine type 0x8664 (X64) + Subsystem 0x000B (EFI boot service driver) + EFI image offset 0x0038 (@0x10C38) +``` + +# VGA rom + +SeaBIOS is an open-source legacy BIOS implementation that implements the standard BIOS calling interfaces that a typical x86 proprietary BIOS implements (https://github.com/coreboot/seabios). +SeaVGABIOS is a sub-project of the SeaBIOS project - it is an open source implementation of a 16bit X86 VGA BIOS +(https://github.com/coreboot/seabios/blob/master/docs/SeaVGABIOS.md). In other words it builds a Legacy Option ROM for a PCI graphic device. + +SeaBIOS uses Kconfig system for the build configuration. Main options for the VGA BIOS are placed under https://github.com/coreboot/seabios/blob/master/vgasrc/Kconfig In this file you can see that one of the options is a OptionROM with a Vendor/Device pair as `1234:1111`. Exactly the one that we saw at QEMU: +``` + config VGA_VID + depends on VGA_PCI + hex + prompt "PCI Vendor ID" if OVERRIDE_PCI_ID + default 0x1013 if VGA_CIRRUS + default 0x1002 if VGA_ATI + default 0x1234 if VGA_BOCHS_STDVGA + default 0x15ad if VGA_BOCHS_VMWARE + default 0x1b36 if VGA_BOCHS_QXL + default 0x1af4 if VGA_BOCHS_VIRTIO + default 0x100b if VGA_GEODEGX2 + default 0x1022 if VGA_GEODELX + default 0x1234 if DISPLAY_BOCHS <-------------- + default 0x0000 + help + Vendor ID for the PCI ROM + + config VGA_DID + depends on VGA_PCI + hex + prompt "PCI Vendor ID" if OVERRIDE_PCI_ID + default 0x00b8 if VGA_CIRRUS + default 0x5159 if VGA_ATI + default 0x1111 if VGA_BOCHS_STDVGA + default 0x0405 if VGA_BOCHS_VMWARE + default 0x0100 if VGA_BOCHS_QXL + default 0x1050 if VGA_BOCHS_VIRTIO + default 0x0030 if VGA_GEODEGX2 + default 0x2081 if VGA_GEODELX + default 0x1111 if DISPLAY_BOCHS <--------------- + default 0x0000 + help + Device ID for the PCI ROM +``` +If you wonder what is `DISPLAY_BOCHS`, here is a help for this option: +``` + config DISPLAY_BOCHS + depends on QEMU + bool "qemu bochs-display support" + select VGA_EMULATE_TEXT + help + Build support for the qemu bochs-display device, which + is basically qemu stdvga without the legacy vga + emulation, supporting only 16+32 bpp VESA video modes + in a linear framebuffer. So this uses cbvga text mode + emulation. + + The bochs-display device is available in qemu + v3.0+. The vgabios works with the qemu stdvga too (use + "qemu -device VGA,romfile=/path/to/vgabios.bin")". +``` + +Let's build this SeaBIOS VGA image. Install necessary packages, download SeaBIOS source and perfrorm build configuration: +``` +$ sudo apt-get install python +$ git clone https://github.com/coreboot/seabios.git +$ cd seabios +$ make menuconfig +``` +In a menuconfig select: +``` +VGA ROM ---> VGA Hardware Type (qemu bochs-display support) +``` +After that execute: +``` +$ make +``` + +After the build resulting VGA Option ROM would be at path `out/vgabios.bin`. As `EfiRom` expects ROM files to have a `*.rom` extension, create a copy of a file with such extension. After that execute `dump` command on this file: +``` +$ cp out/vgabios.bin out/vgabios.rom +$ EfiRom -d out/vgabios.rom +Image 1 -- Offset 0x0 + ROM header contents + Signature 0xAA55 + PCIR offset 0x6E00 + Signature PCIR + Vendor ID 0x1234 + Device ID 0x1111 + Length 0x0018 + Revision 0x0000 + DeviceListOffset 0x00 + Class Code 0x030000 + Image size 0x7000 + Code revision: 0x0001 + MaxRuntimeImageLength 0x00 + ConfigUtilityCodeHeaderOffset 0x9066 + DMTFCLPEntryPointOffset 0x9066 + Indicator 0x80 (last image) + Code type 0x00 +``` +This is the info similar to the one that we saw with our utility on a working QEMU system. You can see that PCI vendor/device pair is set to `1234:1111`. + + +# How QEMU gets these OptionROMs + +The main Makefile in QEMU responsible for OptionROM image creation is https://github.com/qemu/qemu/blob/master/roms/Makefile + +In this Makefile you can see how: +- `seavgabios-%` target is used for the creation of a Legacy SeaVGABIOS OptionROM +- `efi-rom-%` target is used for the creation of an OptionROM with both Legacy and UEFI iPXE code images (it even uses `EfiRom` utility from edk2 for this purpose) + +# Code images for different CPU architectures in OptionROM image + +In the intro I've mentioned that PCI device can have various code images for different CPU architectures. + +Check out this guide as an example https://www.workofard.com/2020/12/aarch64-option-roms-for-amd-gpus/ + +It explains how to add the AMD AARCH64 Gop Driver as another Code Image to the PCI graphic card OptionROM to make the graphic card work at boot time in AArch64 systems. + +It uses `flashrom` utility to download initial PCI card Option ROM firmware and with a help of `EfiRom` adds AMD EFI graphic driver for AArch64 to the list of images in this OptionROM. |