Re: [Xen-devel] [PATCH v5 09/16] x86: add multiboot2 protocol support

[Daniel Kiper <daniel.kiper@xxxxxxxxxx>]

On Thu, Aug 25, 2016 at 05:50:04AM -0600, Jan Beulich wrote:
> >>> On 20.08.16 at 00:43, <daniel.kiper@xxxxxxxxxx> wrote:
> > +        case MULTIBOOT2_TAG_TYPE_MMAP:
> > +            if ( get_mb2_data(tag, mmap, entry_size) < sizeof(*mmap_src) )
> > +                break;
> > +
> > +            mbi_out->flags |= MBI_MEMMAP;
> > +            mbi_out->mmap_length = get_mb2_data(tag, mmap, size);
> > +            mbi_out->mmap_length -= sizeof(multiboot2_tag_mmap_t);
> > +            mbi_out->mmap_length /= get_mb2_data(tag, mmap, entry_size);
> > +            mbi_out->mmap_length *= sizeof(memory_map_t);
> > +
> > +            mbi_out->mmap_addr = alloc_mem(mbi_out->mmap_length);
> > +
> > +            mmap_src = get_mb2_data(tag, mmap, entries);
> > +            mmap_dst = (memory_map_t *)mbi_out->mmap_addr;
> > +
> > +            for ( i = 0; i < mbi_out->mmap_length / sizeof(memory_map_t); 
> > i++ )
> > +            {
> > +                /* Init size member properly. */
> > +                mmap_dst[i].size = sizeof(memory_map_t);
> > +                mmap_dst[i].size -= sizeof(((memory_map_t){0}).size);
> > +                /* Now copy a given region data. */
> > +                mmap_src = (void *)mmap_src + i * get_mb2_data(tag, mmap, 
> > entry_size);
>
> Why do you multiply by i here? The way you've written it you want to
> increment mmap_src by entry_size _at the end_ of each iteration. Or

This is another option. If you wish I can do that.

> else you need a second variable.

I think that former is better.

Daniel

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