From f78c8bf2c64f57d5148bea1a56ade2218a13e4d7 Mon Sep 17 00:00:00 2001 From: Laszlo Ersek Date: Sat, 6 May 2017 18:09:28 +0200 Subject: [PATCH] OvmfPkg/README: document 4MB flash layout Cc: Jordan Justen Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=527 Contributed-under: TianoCore Contribution Agreement 1.0 Signed-off-by: Laszlo Ersek Reviewed-by: Jordan Justen --- OvmfPkg/README | 39 +++++++++++++++++++++++++++++++-------- 1 file changed, 31 insertions(+), 8 deletions(-) diff --git a/OvmfPkg/README b/OvmfPkg/README index 304e69fbe5..33ff9432bb 100644 --- a/OvmfPkg/README +++ b/OvmfPkg/README @@ -245,15 +245,20 @@ longer.) === OVMF Flash Layout === -Like all current IA32/X64 system designs, OVMF's firmware -device (rom/flash) appears in QEMU's physical address space -just below 4GB (0x100000000). +Like all current IA32/X64 system designs, OVMF's firmware device (rom/flash) +appears in QEMU's physical address space just below 4GB (0x100000000). -The layout of the firmware device in memory looks like: +OVMF supports building a 1MB, 2MB or 4MB flash image (see the DSC files for the +FD_SIZE_1MB, FD_SIZE_2MB, FD_SIZE_4MB build defines). The base address for the +1MB image in QEMU physical memory is 0xfff00000. The base address for the 2MB +image is 0xffe00000. The base address for the 4MB image is 0xffc00000. + +Using the 1MB or 2MB image, the layout of the firmware device in memory looks +like: +--------------------------------------- 4GB (0x100000000) | VTF0 (16-bit reset code) and OVMF SEC -| (SECFV) +| (SECFV, 208KB/0x34000) +--------------------------------------- varies based on flash size | | Compressed main firmware image @@ -271,9 +276,27 @@ The layout of the firmware device in memory looks like: | area (56KB/0xe000) +--------------------------------------- base address -OVMF supports building a 1MB or a 2MB flash image. The base address for -a 1MB image in QEMU physical memory is 0xfff00000. The base address for -a 2MB image is 0xffe00000. +Using the 4MB image, the layout of the firmware device in memory looks like: + ++--------------------------------------- base + 0x400000 (4GB/0x100000000) +| VTF0 (16-bit reset code) and OVMF SEC +| (SECFV, 208KB/0x34000) ++--------------------------------------- base + 0x3cc000 +| +| Compressed main firmware image +| (FVMAIN_COMPACT, 3360KB/0x348000) +| ++--------------------------------------- base + 0x84000 +| Fault-tolerant write (FTW) +| Spare blocks (264KB/0x42000) ++--------------------------------------- base + 0x42000 +| FTW Work block (4KB/0x1000) ++--------------------------------------- base + 0x41000 +| Event log area (4KB/0x1000) ++--------------------------------------- base + 0x40000 +| Non-volatile variable storage +| area (256KB/0x40000) ++--------------------------------------- base address (0xffc00000) The code in SECFV locates FVMAIN_COMPACT, and decompresses the main firmware (MAINFV) into RAM memory at address 0x800000. The -- 2.39.2