On Wed, Feb 26, 2014 at 02:37:00PM +0000, Marc Zyngier wrote: > On 25/02/14 18:06, Will Deacon wrote: > > On Wed, Feb 05, 2014 at 01:30:35PM +0000, Marc Zyngier wrote: > >> Linux has some requirements that must be satisfied in order to boot > >> on a system built with a GICv3. > >> > >> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx> > >> --- > >> Documentation/arm64/booting.txt | 7 +++++++ > >> 1 file changed, 7 insertions(+) > >> > >> diff --git a/Documentation/arm64/booting.txt b/Documentation/arm64/booting.txt > >> index a9691cc..4a02ebd 100644 > >> --- a/Documentation/arm64/booting.txt > >> +++ b/Documentation/arm64/booting.txt > >> @@ -131,6 +131,13 @@ Before jumping into the kernel, the following conditions must be met: > >> the kernel image will be entered must be initialised by software at a > >> higher exception level to prevent execution in an UNKNOWN state. > >> > >> + For systems with a GICv3 interrupt controller, it is expected that: > >> + - ID_AA64PFR0_EL1.GIC (bits [27:24]) must have the value 0b0001 > > > > Since ID_AA64PFR0_EL1 is read-only at all exception levels, I don't see the > > value of this statement. > > Think virtualization. A hypervisor can control reads of ID_AA64PFR0_EL1 > by setting HCR_EL2.TID3, and report whatever it wants. Sure, but it seems unreasonable to me that we require a hypervisor to tell a guest about GICv3 if the system happens to have one. What if it wants to emulate a GICv2? In other words, requiring this in booting.txt seems superflous. Will _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
