From mboxrd@z Thu Jan 1 00:00:00 1970 From: linux@arm.linux.org.uk (Russell King - ARM Linux) Date: Fri, 5 Sep 2014 12:05:52 +0100 Subject: [PATCH v2 1/4] arm64, thunder: Add Kconfig option for Cavium Thunder SoC Family In-Reply-To: <20140905104547.GT4703@rric.localhost> References: <1409903205-2762-1-git-send-email-rric@kernel.org> <1409903205-2762-2-git-send-email-rric@kernel.org> <20140905093239.GC30401@n2100.arm.linux.org.uk> <20140905104547.GT4703@rric.localhost> Message-ID: <20140905110552.GH30401@n2100.arm.linux.org.uk> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, Sep 05, 2014 at 12:45:47PM +0200, Robert Richter wrote: > On 05.09.14 10:32:40, Russell King - ARM Linux wrote: > > On Fri, Sep 05, 2014 at 09:46:42AM +0200, Robert Richter wrote: > > > From: Radha Mohan Chintakuntla > > > > > > Increase maximum numbers of cpus to 32. This relates to current > > > maximal possible cpu number. Increasing this to 64 cpus will be a > > > separate patch not part of this enablement patches. > > > > > > Signed-off-by: Radha Mohan Chintakuntla > > > Signed-off-by: Robert Richter > > > --- > > > arch/arm64/Kconfig | 6 ++++++ > > > 1 file changed, 6 insertions(+) > > > > > > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > > > index fd4e81a4e1ce..77fb82b0f684 100644 > > > --- a/arch/arm64/Kconfig > > > +++ b/arch/arm64/Kconfig > > > @@ -134,6 +134,11 @@ source "kernel/Kconfig.freezer" > > > > > > menu "Platform selection" > > > > > > +config ARCH_THUNDER > > > + bool "Cavium Inc. Thunder SoC Family" > > > + help > > > + This enables support for Cavium's Thunder Family of SoCs. > > > + > > > config ARCH_VEXPRESS > > > bool "ARMv8 software model (Versatile Express)" > > > select ARCH_REQUIRE_GPIOLIB > > > @@ -256,6 +261,7 @@ config NR_CPUS > > > range 2 32 > > > depends on SMP > > > # These have to remain sorted largest to smallest > > > + default "32" if ARCH_THUNDER > > > default "8" > > > > Why do you need ARCH_THUNDER? If it's just to change this default, > > No, we need it just to enable all our drivers on the SoC. We want to > enable the SoC by using defconfig + ARCH_THUNDER. As said in my other > mail, I put it here to be able to base all other thunder driver patch > sets on this initial base patch set. Otherwise this particular patch > and also the dtb patch need to be shipped with all other driver patch > sets. This might lead to duplicate submissions of the same patch. > > With doing defconfig + ARCH_THUNDER we also want to enable the max > number of cpus that is currently supported. I only enable 32 cpus > since booting more cpus is untested. There might be problems at the 32 > cpu boundary. Just setting it to 64 does not mean a kernel will > actually boot more than 32 cpus. But if it will be ack'ed, I would be > fine to set NR_CPUS to 32 or 64 in general and independent from > ARCH_THUNDER. > > For simplicity I better drop setting NR_CPUS in this patch. So, ARM64 will get a big long list of "config ARCH_foo" options just to stuff lots of broken select statements into the configuration. Yes, this may have been the norm with ARM, but it's turned out to be more of a problem than a solution, especially as it keeps causing Kconfig warnings when things change in the rest of the kernel tree. The same is true with defconfigs - Linus threatened to delete all ARM defconfigs except one at one point. As I said below, this isn't how stuff is dealt with on x86. What I'm questioning here is the entire ethos of "have an ARCH_foo configuration which sets stuff up for platform foo". > > please don't bother - we don't do this kind of thing on x86, so why > > should it be done here? Just ensure that NR_CPUS is appropriately > > adjusted. Alternatively, look at how x86 deals with this (with > > X86_BIGSMP / MAXSMP). -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net.