Notes below refer to quoted item just above.

> Device mapping table
>   blk0 :Floppy - Alias (null)
>         PciRoot(0x0)/Pci(0x1,0x0)/Floppy(0x0)
>   blk1 :Floppy - Alias (null)
>         PciRoot(0x0)/Pci(0x1,0x0)/Floppy(0x1)
>   blk2 :BlockDevice - Alias (null)
>         PciRoot(0x0)/Pci(0x1,0x1)/Ata(Secondary,Master,0x0)
>
>
> Press ESC in 5 seconds to skip startup.nsh, any other key to continue.
> Press ESC in 4 seconds to skip startup.nsh, any other key to continue.

EFI shell started

> Shell> mem fffe0 32
>   Memory Address 00000000000FFFE0 20 Bytes
>   000FFFE0: EB C3 90 90 90 90 90 90-00 00 00 00 56 54 46 00  *............VTF.*
>   000FFFF0: 90 90 EB AC 90 90 90 90-90 90 90 90 90 90 90 90  *................*

Dump firmware range in legacy F000 segment

> Shell> mem ffffffe0 32
>   Memory Address 00000000FFFFFFE0 20 Bytes
>   FFFFFFE0: EB C3 90 90 90 90 90 90-00 00 00 00 56 54 46 00  *............VTF.*
>   FFFFFFF0: 90 90 EB AC 90 90 90 90-90 90 90 90 90 90 90 90  *................*

Dump firmware range at top of 4GB.

> Shell> mem fff00000 32
>   Memory Address 00000000FFF00000 20 Bytes
>   FFF00000: 01 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00  *................*
>   FFF00010: 78 E5 8C 8C 3D 8A 1C 4F-99 35 89 61 85 C3 2D D3  *x...=..O.5.a..-.*

Dump start of OVMF flash image.  The first 16 bytes are
reserved, and therefore we can program them without a
negative side effect.  Notice I have previously programmed
the first byte from 00 to 01.

> Shell> mm -mmio -w 1 -n fff00000
> MMIO  0x00000000FFF00000 : 0x01

Read the data in the first byte of the rom.

> Shell> mm -mmio -w 1 -n fff00000 70

Request to read the pflash_cfi01 status register.
(0x70 is the command written to address 0xfff00000.)

> Shell> mm -mmio -w 1 -n fff00000
> MMIO  0x00000000FFF00000 : 0x00

Read the status register by reading address 0xfff00000.

> Shell> mm -mmio -w 1 -n fff00000 ff

Put the pflash_cfi01 back into read-data mode.
(0xff is the command for putting the flash into read mode.)

> Shell> mm -mmio -w 1 -n fff00000
> MMIO  0x00000000FFF00000 : 0x01

Notice we read the proper data again...  0x01.

> Shell> mm -mmio -w 1 -n fff00001
> MMIO  0x00000000FFF00001 : 0x00

Now read the data at 0xfff00001.  It is 0x00.

> Shell> mm -mmio -w 1 -n fff00001 10

Put the pflash_cfi01 into programming mode.

> Shell> mm -mmio -w 1 -n fff00001 ab

Program the data at 0xfff00001.  Data is 0xab.

> Shell> mm -mmio -w 1 -n fff00001 ff

Put the pflash_cfi01 back into read-data mode.

> Shell> mm -mmio -w 1 -n fff00001
> MMIO  0x00000000FFF00001 : 0xAB

0xab was programmed into 0xfff00001.

> Shell> mm -mmio -w 1 -n fff00001 70

Request to read the status register.

> Shell> mm -mmio -w 1 -n fff00001
> MMIO  0x00000000FFF00001 : 0x80

bit7 (0x80) indicates device is ready.

> Shell> mm -mmio -w 1 -n fff00001 ff

Back to read-data mode again.

> Shell> mm -mmio -w 1 -n fff00001
> MMIO  0x00000000FFF00001 : 0xAB

The proper data is still returned.

> Shell> reset -s

Shutdown the system...