On Tue, Sep 26, 2017 at 3:40 AM, Stewart Smith <stewart@xxxxxxxxxxxxxxxxxx> wrote: > There are two types of memory reservations firmware can ask the kernel > to make in the device tree: static and dynamic. > See Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt > > If you have greater than 16 entries in /reserved-memory (as we do on > POWER9 systems) you would get this scary looking error message: > [ 0.000000] OF: reserved mem: not enough space all defined regions. > > This is harmless if all your reservations are static (which with OPAL on > POWER9, they are). > > It is not harmless if you have any dynamic reservations after the 16th. > > In the first pass over the fdt to find reservations, the child nodes of > /reserved-memory are added to a static array in of_reserved_mem.c so that > memory can be reserved in a 2nd pass. The array has 16 entries. This is why, > on my dual socket POWER9 system, I get that error 4 times with 20 static > reservations. > > We don't have a problem on ppc though, as in arch/powerpc/kernel/prom.c > we look at the new style /reserved-ranges property to do reservations, > and this logic was introduced in 0962e8004e974 (well before any powernv > system shipped). > > A Google search shows up no occurances of that exact error message, so we're > probably safe in that no machine that people use has memory not being reserved > when it should be. > > The simple fix is to bump the length of the array to 32 which "should be > enough for everyone(TM)". The simple fix of not recording static allocations > in the array would cause problems for devices with "memory-region" properties. > A more future-proof fix is likely possible, although more invasive and this > simple fix is perfectly suitable in the meantime while a more future-proof > fix is developed. > > Signed-off-by: Stewart Smith <stewart@xxxxxxxxxxxxxxxxxx> > --- > drivers/of/of_reserved_mem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Applied. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
