# Which drivers are compiled into the kernel.
#
#   y   compiled in, and enabled: it is offered every device it can drive
#   n   not compiled in: the code is not linked and the kernel never knows it
#
# Everything is y unless it says otherwise. Change a line, or override one for
# a single build:
#
#     make DRV_E1000=n DRV_NVME=n
#
# A changed value rebuilds only kernel/drivers/registry.o and the link.
#
# These are the drivers that can be left out cleanly: nothing else in the kernel
# calls them, they are only offered a device by the registry
# (kernel/drivers/registry.c). The others cannot be, because the rest of the
# kernel calls into them directly, and are not listed:
#
#     vga_fb      the boot framebuffer: the console and the crash screen draw on it
#     xhci, usb core, usb hid / storage / hub
#                 the keyboard and the root disk can arrive over USB, bio.c and
#                 the hotplug thread call in, and so does the I2C-HID touchpad
#     PS/2, IDE, the 16550 UART
#                 fixed-address legacy devices (kernel/dev/)
#
# Linux's own drivers, run in a process by ldlsd, are not here: they are files in
# the image (make ldls-r8169), not code in the kernel.

# --- display --------------------------------------------------------------
DRV_VGA_PCI    = y     # the stdvga/Bochs card (the framebuffer driver stays regardless)
DRV_VIRTIO_GPU = y     # QEMU's virtio-gpu: mode setting and an explicit flush

# --- network ----------------------------------------------------------------
DRV_E1000      = y     # Intel 8254x and 8257x
DRV_RTL8139    = y     # Realtek 8139 (the one Realtek part QEMU emulates)
# The native RTL8168/8111 driver. Off by default because the laptop's NIC is
# driven by Linux's r8169 under LDLS (etc/schinit/ldls-r8169.job), and a driver
# here would claim the device first. Turn it on for a machine without that job.
DRV_R8169      = n

# --- storage ----------------------------------------------------------------
DRV_AHCI       = y     # SATA
DRV_NVME       = y     # NVMe SSDs

# --- audio ------------------------------------------------------------------
DRV_AC97       = y     # Intel AC'97 (QEMU's and old boards')