Hi Peter, On Mon, Jan 30, 2017 at 12:26 PM, Peter Maydell <peter.maydell@xxxxxxxxxx> wrote: > On 30 January 2017 at 17:08, Jintack Lim <jintack@xxxxxxxxxxxxxxx> wrote: >> On Sun, Jan 29, 2017 at 10:44 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote: >>> Shouldn't we take the ENABLE bit into account? The ARMv8 ARM version I >>> have at hand (version h) seems to indicate that we should, but we should >>> check with the latest and greatest... >> >> Thanks! I was not clear about this. I have ARM ARM version k, and it >> says that 'When the value of the ENABLE bit is 0, the ISTATUS field is >> UNKNOWN.' So I thought the istatus value doesn't matter if ENABLE is >> 0, and just set istatus bit regardless of ENABLE bit. If this is not >> what the manual meant, then I'm happy to fix this. > > It looks like the spec has been relaxed between the doc version > that Marc was looking at and the current one. So it's OK for > an implementation to either (a) set ISTATUS to 0 if ENABLE > is 0, or (b) do what you've done and set ISTATUS according > to the timer comparison whether ENABLE is clear or not > (or even (c) set ISTATUS to a random value if ENABLE is clear, > and other less likely choices). > I think we should add a comment to note that it's architecturally > UNKNOWN and we've made a choice for our implementation convenience. Thanks for the clarification. I'll put a comment in v3. > > thanks > -- PMM >
