x86: qemu: Enable NVMe driver

QEMU supports NVMe emulation. Enable the NVMe driver on QEMU x86.
Signed-off-by: NBin Meng <bmeng.cn@gmail.com>
Reviewed-by: NTom Rini <trini@konsulko.com>

configs/qemu-x86_defconfig

@@ -37,6 +37,7 @@ CONFIG_EFI_PARTITION=y
 CONFIG_REGMAP=y
 CONFIG_SYSCON=y
 CONFIG_CPU=y
+CONFIG_NVME=y
 CONFIG_USB_STORAGE=y
 CONFIG_USB_KEYBOARD=y
 CONFIG_FRAMEBUFFER_SET_VESA_MODE=y

doc/README.nvme

@@ -76,3 +76,11 @@ Of course, file system command can be used on the NVMe hard disk as well:
 
   => fatload nvme 0:1 a0000000 /kernel.itb
   => bootm a0000000
+
+Testing NVMe with QEMU x86
+--------------------------
+QEMU supports NVMe emulation and we can test NVMe driver with QEMU x86 running
+U-Boot. Please see README.x86 for how to build u-boot.rom image for QEMU x86.
+
+Example command line to call QEMU x86 below with emulated NVMe device:
+$ ./qemu-system-i386 -drive file=nvme.img,if=none,id=drv0 -device nvme,drive=drv0,serial=QEMUNVME0001 -bios u-boot.rom