[PATCH v31 02/12] arm64: limit memory regions based on DT property, usable-memory-range

AKASHI Takahiro
2017-02-02T04:21:36Z

On Wed, Feb 01, 2017 at 03:07:00PM +0000, Mark Rutland wrote:
> Hi,
>
> On Wed, Feb 01, 2017 at 09:46:21PM +0900, AKASHI Takahiro wrote:
> > +static int __init early_init_dt_scan_usablemem(unsigned long node,
> > + const char *uname, int depth, void *data)
> > +{
> > + struct memblock_region *usablemem = (struct memblock_region *)data;
>
> Nit: unnecessary cast.

OK

> > + const __be32 *reg;
> > + int len;
> > +
> > + usablemem->size = 0;
>
> Could we please lift this assignment/initialisation into the caller...
>
> > +
> > + if (depth != 1 || strcmp(uname, "chosen") != 0)
> > + return 0;
> > +
> > + reg = of_get_flat_dt_prop(node, "linux,usable-memory-range", &len);
> > + if (!reg || (len < (dt_root_addr_cells + dt_root_size_cells)))
> > + return 1;
> > +
> > + usablemem->base = dt_mem_next_cell(dt_root_addr_cells, &reg);
> > + usablemem->size = dt_mem_next_cell(dt_root_size_cells, &reg);
> > +
> > + return 1;
> > +}
> > +
> > +static void __init fdt_enforce_memory_region(void)
> > +{
> > + struct memblock_region reg;
>
> ... e.g. have:
>
> struct memblock_region reg = {
> .size = 0,
> };

Sure

> That saves us from making unnecessary assignments to the size field, and
> makes it clear that reg.size has definitely been initialised, regardless
> of what of_scan_flat_dt() happens to do.
>
> With that:
>
> Acked-by: Mark Rutland <mark.rutland@arm.com>

Thanks,
-Takahiro AKASHI

> Thanks,
> Mark.
>
> > +
> > + of_scan_flat_dt(early_init_dt_scan_usablemem, &reg);
> > +
> > + if (reg.size)
> > + memblock_cap_memory_range(reg.base, reg.size);
> > +}
> > +
> > void __init arm64_memblock_init(void)
> > {
> > const s64 linear_region_size = -(s64)PAGE_OFFSET;
> >
> > + /* Handle linux,usable-memory-range property */
> > + fdt_enforce_memory_region();
> > +
> > /*
> > * Ensure that the linear region takes up exactly half of the kernel
> > * virtual address space. This way, we can distinguish a linear address
> > --
> > 2.11.0
> >