Re: [PATCH v2 4/5] OvmfPkg/README: document 4MB flash layout

[Laszlo Ersek <lersek@redhat.com>]

On 05/18/17 17:14, Laszlo Ersek wrote:
> Cc: Jordan Justen <jordan.l.justen@intel.com>
> Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=527
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Laszlo Ersek <lersek@redhat.com>
> ---
> 
> Notes:
>     v2:
>     - no changes
> 
>  OvmfPkg/README | 39 ++++++++++++++++----
>  1 file changed, 31 insertions(+), 8 deletions(-)
> 
> diff --git a/OvmfPkg/README b/OvmfPkg/README
> index 304e69fbe545..33ff9432bb3e 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
> 

Commit f78c8bf2c64f.