Only scan the root bus in early PCI quirks.
PATCH 1/1 Only scan the root bus in early PCI quirks.
Only scan the root bus in early PCI quirks.
We found a situation on Linus' machine that the Nvidia timer quirk hit on a Intel chipset system. The problem is that the system has a fancy Nvidia card with an own PCI bridge, and the early-quirks code looking for any NVidia bridge triggered on it incorrectly. This didn't lead a boot failure by luck, but the timer routing code selecting the wrong timer first and some ugly messages. It might lead to real problems on other systems.
Update: according to Suresh the problem can cause real boot failures together with x2apic.
I checked all the devices which are currently checked for by early_quirks and it turns out they are all located in the root bus zero.
So change the early-quirks loop to only scan bus 0. This incidently also saves quite some unnecessary scanning work, because early_quirks doesn't go through all the non root busses. I don't expect that it will make the boot visible faster, but doing less work is still good.
The graphics card is not on bus 0, so it is not matched anymore.
--- arch/x86/kernel/early-quirks.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-)
arch/x86/kernel/early-quirks.c +14 -8
@@ -214,6 +214,12 @@void (*f)(int num,int slot,int func); }; +/* +* Only works for devices on the root bus. If you add any devices +* not on bus 0 readd another loop level in early_quirks(). But +* be careful because at least the Nvidia quirk here relies on +* only matching on bus 0. +*/ static struct chipset early_qrk[]__initdata = { {PCI_VENDOR_ID_NVIDIA ,PCI_ANY_ID ,PCI_CLASS_BRIDGE_PCI ,PCI_ANY_ID ,QFLAG_APPLY_ONCE , nvidia_bugs },
@@ -284,17 +290,17 @@void __init early_quirks (void ) { -int num, slot, func; +int slot, func;if (!early_pci_allowed ())return ;/* Poor man's PCI discovery */ -for (num =0 ; num <32 ; num++) -for (slot =0 ; slot <32 ; slot++) -for (func =0 ; func <8 ; func++) { -/* Only probe function 0 on single fn devices */ -if (check_dev_quirk (num, slot, func)) -break ; - } +/* Only scan the root bus */ +for (slot =0 ; slot <32 ; slot++) +for (func =0 ; func <8 ; func++) { +/* Only probe function 0 on single fn devices */ +if (check_dev_quirk (0 , slot, func)) +break ; + } }