On 13.02.2011, at 10:34, David Gibson wrote:
> On Sat, Feb 12, 2011 at 04:57:39PM +0100, Alexander Graf wrote:
>> On 12.02.2011, at 15:54, David Gibson wrote:
> [snip]
>>> + if (rb & (0x1000 - env->slb_nr))
>>
>> Braces...
>
> Oops, yeah. These later patches in the series I haven't really
> audited for coding style adequately yet. I'll fix these before the
> next version.
>
> [snip]
>>> + return -1; /* 1T segment on MMU that doesn't support it */
>>> +
>>> + /* We stuff a copy of the B field into slb->esid to simplify
>>> + * lookup later */
>>> + slb->esid = (rb & (SLB_ESID_ESID | SLB_ESID_V)) |
>>> + (rs >> SLB_VSID_SSIZE_SHIFT);
>>
>> Wouldn't it be easier to add another field?
>
> Easier for what? The reason I put these bits in here is that the rest
> of the things slb_lookup() needs to scan for are all in the esid
> field, so putting B in there means slb_lookup() needs only one
> comparison per-slot, per segment size.
Hrm - but it also needs random & ~3 masking in other code which is very
unpretty. Comparing two numbers really shouldn't hurt performance too much, but
makes the code better maintainable.
struct slb_entry {
uint64_t esid;
uint64_t vsid;
int b;
}
or so :).
Alex
