Huh, thought I did a more complete reply to this. Must have farted on it.
Rusty Russell wrote:
> Thanks Jeremy, I've actually taken time to finally review this in detail (I'm
> assuming you'll refactor as necessary after the x86 arch merger).
>
Yep.
>> +struct paravirt_ops paravirt_ops;
>> +
>>
>
> Do you actually need to define this? See below...
>
>
>> +DEF_NATIVE(, ud2a, "ud2a");
>>
>
> Hmm, that's ugly. It was ugly before, but it's uglier now. Maybe just
> use "unsigned char ud2a[] = { 0x0f, 0x0b };" in paravirt_patch_default?
>
Yeah, its not pretty. I'll have another go.
>> }
>>
>> struct paravirt_ops paravirt_ops = {
>>
> ...
>
>> + .pv_info = {
>> + .name = "bare hardware",
>> + .paravirt_enabled = 0,
>> + .kernel_rpl = 0,
>> + .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */
>> + },
>>
>
> This is the bit I don't get. Why not just declare struct pv_info pvinfo, etc,
> and use the declaration of struct paravirt_ops to get your unique
> offset-based identifiers for patching?
>
Given an op id number in .parainstructions, the patching code needs to
be able to index into something to get the corresponding function
pointer. If each pv_* structure is its own little unrelated structure,
then the id has to be a <structure, id> tuple, which just complicates
things. If I pack them all into a single structure then it becomes a
simple offset calculation.
That said, there's no need for pv_info to be in that structure, since it
contains no function pointers. I'll move it out.
J
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