RE: [PATCH V4] multiboot2: Implement quirk-modules-after-kernel

["Chen, Zide" <zide.chen@intel.com>]

Hi Daniel,

> -----Original Message-----
> From: Chen, Zide
> Sent: Thursday, April 16, 2020 10:41 AM
> To: 'Daniel Kiper' <dkiper@net-space.pl>
> Cc: grub-devel@gnu.org
> Subject: RE: [PATCH V4] multiboot2: Implement quirk-modules-after-kernel
> 
> > >             +------------------+
> > > u16     | type = 22       |
> > > u16     | flags               |
> > > u32     | size = 20        |
> > > u32     | min_addr      |
> >
> > s/u32/u64/
> 
> Currently modules are loaded at 32bit address only. But yes, I agree that 'u64' would
> make it more flexible.
> 
> > > u32     | max_addr     |
> >
> > s/u32/u64/
> >
> > > u32     | preference   |
> >
> > Please put preference immediately behind the size.
> Sure, will do.

Just noticed that if we change min/max_addr to u64, and move preference right after size,
it could have struct packing issue. For example:

struct multiboot_header_tag_module_relocatable
{
  multiboot_uint16_t type;
  multiboot_uint16_t flags;
  multiboot_uint32_t size;
  multiboot_uint32_t preference; 
  multiboot_uint64_t min_addr;  // address is compiler dependent
  multiboot_uint64_t max_addr;
};

So I still propose to put preference after max_addr. I wrote the code based on this proposed new tag,
and will send out the doc change and implementation for review shortly.

-Zide