On 03/27/2012 01:44 PM, Scott Wood wrote: > On 03/27/2012 10:21 AM, Stuart Yoder wrote: >> On Tue, Mar 27, 2012 at 8:30 AM, Kumar Gala <ga...@kernel.crashing.org> >> wrote: >>> >>> On Mar 27, 2012, at 7:15 AM, Varun Sethi wrote: >>> >>>> FSL MPIC supports 16 bit vectors so our vector number space isn't >>>> restricted to 256 vectors. We should use the MPIC_LARG_VECTORS flag >>>> while intializing the MPIC. This also prevents us from eating in to >>>> hardware vector number space (MSIs) while setting up internal sources. >>> >>> What is driving this change? >> >> Whats driving the change is proper handling of error interrupts. Right >> now error interrupts (muxed on int 16) are treated as a shared >> interrupt source. We want each to be handled as a individual interrupt >> source...thus the desire to support more than 256 interrupts. > > We don't actually need more than 256 interrupts for this (the individual > error interrupts are not counted against this). But unless we change > how vectors are allocated, we need vectors >= 256, since we have MSIs > close enough to 256 that under the current scheme the IPIs, timers, and > such collide with the third MSI bank.
Note that this is the case today even without the error interrupt stuff -- the highest vector used by MSIs on MPIC 4.1 is 0xf7, and we have 13 special vectors (4 IPIs, 8 timers, and spurious). -Scott _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
