On Sun, Feb 10, 2019 at 04:33:42PM -0800, Frank Rowand wrote:
> Hi David,
>
> On 2/5/19 8:39 PM, David Gibson wrote:
> > On Thu, Jan 24, 2019 at 07:20:48PM +0900, AKASHI Takahiro wrote:
> >> This function will append an address range property using parent node's
> >> "#address-cells" and "#size-cells" properties.
> >>
> >> It will be used in implementing kdump with kexec_file_load system call
> >> at linux kernel for arm64 once it is merged into kernel tree.
> >>
> >> Signed-off-by: AKASHI Takahiro <takahiro.akashi@xxxxxxxxxx>
> >
> > Sorry I've taken so long to look at this.
> >
> >> ---
> >> libfdt/fdt_addresses.c | 43 ++++++++++++++++++++++++++++++++++++++++++
> >> libfdt/libfdt.h | 37 ++++++++++++++++++++++++++++++++++++
> >> 2 files changed, 80 insertions(+)
> >>
> >> diff --git a/libfdt/fdt_addresses.c b/libfdt/fdt_addresses.c
> >> index f13a87dfa068..6f13a7bbb6a3 100644
> >> --- a/libfdt/fdt_addresses.c
> >> +++ b/libfdt/fdt_addresses.c
> >> @@ -95,3 +95,46 @@ int fdt_size_cells(const void *fdt, int nodeoffset)
> >> return 1;
> >> return val;
> >> }
> >> +
> >> +static void cpu64_to_fdt_cells(uint8_t *prop, uint64_t val, int cells)
> >> +{
> >> + fdt32_t val32;
> >> +
> >> + while (cells) {
> >> + val32 = cpu_to_fdt32(val >> (32 * (--cells)));
>
> < snip >
>
> The line of code above led me to look at the libfdt version of cpu_to_fdt32().
> If I am looking in the correct place, libfdt/libfdt_env.h, then I only see
> a version for little endian systems. Am I missing something, or does libfdt
> assume little endian system and not support running on a big endian
> system?
No, despite not using an #ifdef the versions there work for both
little and big endian systems. The trick is that on one side we
access bytes by index a pointer and on the other side we access bytes
using integer shifts. Those relate to each other differently on big
vs. little endian systems.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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