From mboxrd@z Thu Jan 1 00:00:00 1970 From: arnd@arndb.de (Arnd Bergmann) Date: Mon, 08 Sep 2014 15:00:47 +0200 Subject: [PATCH] arm64, defconfig: Increase NR_CPUS default to 64 In-Reply-To: <1410176689-20020-1-git-send-email-rric@kernel.org> References: <1410176689-20020-1-git-send-email-rric@kernel.org> Message-ID: <3450151.nDuN2aF2Xl@wuerfel> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Monday 08 September 2014 13:44:48 Robert Richter wrote: > From: Robert Richter > > Raising the current maximum limit to 64. This is needed for Cavium's > Thunder systems that will have at least 48 cores per die. > > The change keeps the current memory footprint in cpu mask structures. > It does not break existing code. Setting the maximum to 64 cpus still > boots systems with less cpus. > > Mark's Juno happily booted with a NR_CPUS=64 kernel. > > Tested on our Thunder system with 48 cores. We could see interrupts to > all cores. > > Cc: Radha Mohan Chintakuntla > Cc: Mark Rutland > Signed-off-by: Robert Richter > Acked-by: Arnd Bergmann FWIW, have you tried what happens when you increase the number further? We have architectures on which we support thousands of CPUs, so I wonder if there is a point at which this stops working on ARM64. Are you able to compile and boot a kernel built with e.g. NR_CPUS=256 or 4096 on your hardware? Arnd