Add configurable ramstage support for minimal PCI scanning
This CL has changes that allow us to enable a configurable
ramstage, and one change that allows us to minimize PCI
scanning. Minimal scanning is a frequently requested feature.
To enable it, we add two new variables to src/Kconfig
CONFIGURABLE_RAMSTAGE
is the overall variable controlling other options for minimizing the
ramstage.
MINIMAL_PCI_SCANNING is how we indicate we wish to enable minimal
PCI scanning.
Some devices must be scanned in all cases, such as 0:0.0.
To indicate which devices we must scan, we add a new mandatory
keyword to sconfig
It is used in place of on, off, or hidden, and indicates
a device is enabled and mandatory. Mandatory
devices are always scanned. When MINIMAL_PCI_SCANNING is enabled,
ONLY mandatory devices are scanned.
We further add support in src/device/pci_device.c to manage
both MINIMAL_PCI_SCANNING and mandatory devices.
Finally, to show how this works in practice, we add mandatory
keywords to 3 devices on the qemu-q35.
TEST=
1. This is tested and working on the qemu-q35 target.
2. On CML-Hatch
Before CL:
Total Boot time: ~685ms
After CL:
Total Boot time: ~615ms
Change-Id: I2073d9f8e9297c2b02530821ebb634ea2a5c758e
Signed-off-by: Ronald G. Minnich <rminnich@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36221
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Jeremy Soller <jeremy@system76.com>
diff --git a/src/include/device/device.h b/src/include/device/device.h
index c3a1106..333ac5d 100644
--- a/src/include/device/device.h
+++ b/src/include/device/device.h
@@ -119,7 +119,10 @@
unsigned int initialized : 1; /* 1 if we have initialized the device */
unsigned int on_mainboard : 1;
unsigned int disable_pcie_aspm : 1;
- unsigned int hidden : 1; /* set if we should hide from UI */
+ /* set if we should hide from UI */
+ unsigned int hidden : 1;
+ /* set if this device is used even in minimum PCI cases */
+ unsigned int mandatory : 1;
u8 command;
uint16_t hotplug_buses; /* Number of hotplug buses to allocate */