Re: [RFC v2-fix 1/1] x86/boot: Add a trampoline for APs booting in 64-bit mode

[Kuppuswamy, Sathyanarayanan]

Hi Dan,

On 5/17/21 9:08 PM, Dan Williams wrote:
> > SYM_DATA_START_LOCAL(tr_idt)
> >           .short  0
> >           .quad   0
> > SYM_DATA_END(tr_idt)
> This format implies that tr_idt is reserving space for 2 distinct data
> structure attributes of those sizes, can you just put those names here
> as comments? Otherwise the .fill format is more compact.

Initially its 6 bytes (2 bytes for IDT limit, 4 bytes for 32 bit linear
start address). This patch extends it by another 4 bytes for supporting
64 bit mode.

2 bytes IDT limit (.short)
8 bytes for 64 bit IDT start address (.quad)

This info is included in commit log. But I will add comment here as you
have mentioned.

Will following comment log do ?

/* Use 10 bytes for IDT (in 64 bit mode), 8 bytes for IDT start address
   2 bytes for IDT limit size */

--
Sathyanarayanan Kuppuswamy
Linux Kernel Developer