Re: [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-05-06 Thread Peter Maydell
On 6 May 2015 at 15:05, Peter Crosthwaite wrote: > What I am most worried about (and I need to run some tests to really > confirm facts) is what happens if a CPU WFIs. Should the PMCCNTR > continue on or hold its value? If we match instruction execution to > PMCCNTR to the PMCCNTR will freeze. Se

Re: [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-05-06 Thread Peter Crosthwaite
On Fri, May 1, 2015 at 7:35 AM, Christopher Covington wrote: > On Thu, Apr 30, 2015 at 9:24 PM, Peter Crosthwaite > wrote: >> On Thu, Apr 30, 2015 at 11:14 AM, Christopher Covington >> wrote: >>> Present a system with an instructions per cycle of exactly one. >>> This makes it less likely a user

Re: [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-05-04 Thread Paolo Bonzini
On 01/05/2015 00:02, Peter Maydell wrote: > On 30 April 2015 at 22:33, Christopher Covington > wrote: >> On Apr 30, 2015 2:28 PM, "Peter Maydell" wrote: >>> Are you really really sure the _raw function is the correct one? >>> Nowhere else in the codebase calls it except the other wrappers >>> i

Re: [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-05-01 Thread Christopher Covington
On Thu, Apr 30, 2015 at 9:24 PM, Peter Crosthwaite wrote: > On Thu, Apr 30, 2015 at 11:14 AM, Christopher Covington > wrote: >> Present a system with an instructions per cycle of exactly one. >> This makes it less likely a user will mistake the cycle counter >> values as meaningful and makes calc

Re: [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-04-30 Thread Peter Crosthwaite
On Thu, Apr 30, 2015 at 11:14 AM, Christopher Covington wrote: > Present a system with an instructions per cycle of exactly one. > This makes it less likely a user will mistake the cycle counter > values as meaningful and makes calculations involving cycles > trivial while preserving the necessary

Re: [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-04-30 Thread Peter Maydell
On 30 April 2015 at 22:33, Christopher Covington wrote: > On Apr 30, 2015 2:28 PM, "Peter Maydell" wrote: >> Are you really really sure the _raw function is the correct one? >> Nowhere else in the codebase calls it except the other wrappers >> in cpu.c which provide a sane view of the instruction

Re: [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-04-30 Thread Christopher Covington
Hi Peter, Thanks for taking a look. On Apr 30, 2015 2:28 PM, "Peter Maydell" wrote: > > On 30 April 2015 at 19:14, Christopher Covington > wrote: > > Present a system with an instructions per cycle of exactly one. > > This makes it less likely a user will mistake the cycle counter > > values as

Re: [Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-04-30 Thread Peter Maydell
On 30 April 2015 at 19:14, Christopher Covington wrote: > Present a system with an instructions per cycle of exactly one. > This makes it less likely a user will mistake the cycle counter > values as meaningful and makes calculations involving cycles > trivial while preserving the necessary proper

[Qemu-devel] [RFC 5/5] arm: Simplify cycle counter

2015-04-30 Thread Christopher Covington
Present a system with an instructions per cycle of exactly one. This makes it less likely a user will mistake the cycle counter values as meaningful and makes calculations involving cycles trivial while preserving the necessary property of the cycle counter register as monotonically increasing. Si