Re: [RFC/PATCH] of: Mark property::value as const

On 02/23/17 14:09, Rob Herring wrote:

On Thu, Feb 23, 2017 at 2:58 PM, Frank Rowand [off-list ref] wrote:

quoted

On 02/23/17 11:54, Frank Rowand wrote:

quoted

On 02/13/17 18:50, Stephen Boyd wrote:

quoted

The 'blob' we pass into populate_properties() is marked as const,
but we cast that const away when we assign the result of
fdt_getprop_by_offset() to pp->value. Let's mark value as const
instead, so that code can't mistakenly write to the value of the
property that we've so far advertised as const.

Unfortunately, this exposes a problem with the fdt resolver code,
where we overwrite the value member of properties of phandles to
update them with their final value. Add a comment for now to
indicate where we're potentially writing over const data.

The resolver should not be over writing anything in the FDT.  I'll
look at what is going on there.

The FDT we expose to user space should be the FDT we booted with,
not something later modified.

It seems that /sys/firmware/fdt is not documented.  I'll look into
fixing that.

That's because the "official" interface is /proc/device-tree/ which is
now a symlink. IIRC, it is documented to use /proc/device-tree, not
the sysfs path.

Rob
.

Documentation/ABI/testing/sysfs-firmware-ofw describes
/sys/firmware/devicetree/* but not /sys/firmware/fdt


It also describes the /proc/device-tree symlink to
/sys/firmware/devicetree/base as the official
stable ABI, as you mentioned.

So it is just fdt that I have not found the documentation
for.

-Frank
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