Re: [PATCH 06/13] x86/efi: Build our own EFI services pointer table

[Matt Fleming <matt-HNK1S37rvNbeXh+fF434Mdi2O/JbrIOy@public.gmane.org>]

On Thu, 27 Feb, at 12:09:21PM, H. Peter Anvin wrote:
> 
> That being said, is there a reason we can't simply write this as:
> 
> 	efi_system_table_##bits##_t table;
> 
> 	/* ... */
> 
> 	func = (typeof(func))(unsigned long)table->con_out;
> 	c->text_output = *func;

Oh, yeah that's much better. I was being overly cautious with trying to
not dereference the pointers in the regular efi_system_table_t, and what
you've written is much more compact both in terms of C and generated
object code. Things end up looking like this,

---

#define BOOT_SERVICES(bits)						\
static void setup_boot_services##bits(struct efi_config *c)		\
{									\
	efi_system_table_##bits##_t *table;				\
	efi_boot_services_##bits##_t *bt;				\
									\
	table = (typeof(table))sys_table;				\
									\
	c->text_output = table->con_out;				\
									\
	bt = (typeof(bt))(unsigned long)(table->boottime);		\
									\
	c->allocate_pool = bt->allocate_pool;				\
	c->allocate_pages = bt->allocate_pages;				\
	c->get_memory_map = bt->get_memory_map;				\
	c->free_pool = bt->free_pool;					\
	c->free_pages = bt->free_pages;					\
	c->locate_handle = bt->locate_handle;				\
	c->handle_protocol = bt->handle_protocol;			\
	c->exit_boot_services = bt->exit_boot_services;			\
}
BOOT_SERVICES(32);
BOOT_SERVICES(64);

-- 
Matt Fleming, Intel Open Source Technology Center