On 07/15/2015 01:24 AM, Sreekanth Reddy wrote: > On Tue, Jul 14, 2015 at 10:36:58PM -0700, Yinghai Lu wrote: >> On Tue, Jul 14, 2015 at 9:49 PM, Sreekanth Reddy >> <sreekanth.reddy@xxxxxxxxxxxxx> wrote: >>> Driver crashes if the BIOS do not set up at least one >>> memory I/O resource. This failure can happen if the device is too >>> slow to respond during POST and is missed by the BIOS, but Linux >>> then detects the device later in the boot process. >> >> But pci subsystem should assign resources to those unassigned BAR. >> >> Do you mean even kernel can not assign resource to them? or it takes so long for >> mpt FW to get ready? > > This is not an issue from mpt FW. > > I have just kept the same description provide by Timothy in his > initial patch. > > But I observe that their may be chance of getting "unable to handle > kernel NULL pointer dereference" kernel panic if no Memory Resource > available in the PCI subsystem. So agreed to the Timothy proposal of > aborting the driver initialization if it doesn't detect any Memory > resource instead of whole system get into panic state. > >> >> Thanks >> >> Yinghai On some systems Linux is unable / unwilling to assign a BAR if the BIOS does not assign one at startup. I didn't look into the Linux allocator side of things in much detail, but it is quite possible that Linux is unaware the device only has partial resources assigned. -- Timothy Pearson Raptor Engineering +1 (415) 727-8645 http://www.raptorengineeringinc.com -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
