On 06.01.2012, at 20:32, Scott Wood <scottwood@xxxxxxxxxxxxx> wrote: > On 01/05/2012 10:15 PM, Alexander Graf wrote: >> Right now we transfer a static struct every time we want to get or set >> registers. Unfortunately, over time we realize that there are more of >> these than we thought of before and the extensibility and flexibility of >> transferring a full struct every time is limited. >> >> So this is a new approach to the problem. With these new ioctls, we can >> get and set a single register that is identified by an ID. This allows for >> very precise and limited transmittal of data. When we later realize that >> it's a better idea to shove over multiple registers at once, we can reuse >> most of the infrastructure and simply implement a GET_MANY_REGS / SET_MANY_REGS >> interface. >> >> The only downpoint I see to this one is that it needs to pad to 1024 bits >> (hardware is already on 512 bit registers, so I wanted to leave some room) >> which is slightly too much for transmitting only 64 bits. But if that's all >> the tradeoff we have to do for getting an extensible interface, I'd say go >> for it nevertheless. > > The comment about padding is no longer relevant. > >> +/* >> + * Architecture specific registers are to be defined in arch headers and >> + * ORed with the arch identifier. >> + */ >> +#define KVM_REG_PPC 0x1000000000000000ULL >> +#define KVM_REG_X86 0x2000000000000000ULL >> +#define KVM_REG_IA64 0x3000000000000000ULL >> +#define KVM_REG_ARM 0x4000000000000000ULL >> +#define KVM_REG_S390 0x5000000000000000ULL >> + >> +#define KVM_REG_SIZE_SHIFT 52 >> +#define KVM_REG_SIZE_MASK 0x00f0000000000000ULL >> +#define KVM_REG_SIZE_U8 0x0000000000000000ULL >> +#define KVM_REG_SIZE_U16 0x0010000000000000ULL >> +#define KVM_REG_SIZE_U32 0x0020000000000000ULL >> +#define KVM_REG_SIZE_U64 0x0030000000000000ULL >> +#define KVM_REG_SIZE_U128 0x0040000000000000ULL >> +#define KVM_REG_SIZE_U256 0x0050000000000000ULL >> +#define KVM_REG_SIZE_U512 0x0060000000000000ULL >> +#define KVM_REG_SIZE_U1024 0x0070000000000000ULL > > Why not just encode directly as number of bytes? Because this is 1 << n bytes :) Alex > > -Scott > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
