Re: [Xen-devel] [RFC v1 4/8] x86/init: add linker table support

["Luis R. Rodriguez" <mcgrof@xxxxxxxxxxxxxxxx>]

On Thu, Jan 21, 2016 at 11:52 AM, H. Peter Anvin <hpa@xxxxxxxxx> wrote:
> On 01/21/16 11:50, H. Peter Anvin wrote:
>>
>> Right... we already do that.
>>
>> I don't even think you need to initialize any tables.  At least on i386,
>> we have to do this in assembly code.  However, it is just a simple table
>> walk.  :)
>>
>
> It might make more sense to make subarch its own table, though, although
> I haven't looked at your code in enough detail to say.

The gist of it:

void x86_init_fn_early_init() {
  for_each_table_entry(init_fn, X86_INIT_FNS) {
     if supported subarc
      init_fn->early_init();
}

void x86_init_fn_setup_arch() {
  for_each_table_entry(init_fn, X86_INIT_FNS) {
     if supported subarc
      init_fn->setup_archt();
}

Right now the code defines just an init routine at the stage for
x86_64_start_reservations(), we call the callback early_init(), ie
setup_arch() doesn't exist yet. Since certain routines can run on
either Xen or bare-metal we allow a bitwise OR for the subarch as a
bitmask. I'll think a bit more about how to use subarch for a table,
but can't fit it yet. I'd like to later revise kfree'ing unused
sections, and a table per subarch might be nice for that, but
otherwise this flow seems easy to follow, so if we can kfree sections
within a table we could still accomplish that later.

  Luis

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