| Message ID | 1395257399-359545-45-git-send-email-arnd@arndb.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Mar 19, 2014 at 08:29:41PM +0100, Arnd Bergmann wrote: > This adds a new Kconfig option for the Integrator platform to > choose between ARMv4/ARMv5 based CPUs and those based on ARMv6/ARMv7, > which is required because we cannot have both classes enabled in the > same kernel at compile time. Wouldn't it just be easier to make the older CPUs depend on !CPU_V6 && !CPU_V7 rather than trying to hack this for each platform?
On Wednesday 19 March 2014 20:49:47 Russell King - ARM Linux wrote: > On Wed, Mar 19, 2014 at 08:29:41PM +0100, Arnd Bergmann wrote: > > This adds a new Kconfig option for the Integrator platform to > > choose between ARMv4/ARMv5 based CPUs and those based on ARMv6/ARMv7, > > which is required because we cannot have both classes enabled in the > > same kernel at compile time. > > Wouldn't it just be easier to make the older CPUs depend on > !CPU_V6 && !CPU_V7 rather than trying to hack this for each platform? It's only two platforms: integrator and realview. Actually I took two different approaches on these, and wanted to make up my mind first which one is better. Any suggestion? I have a mild preference to always using 'select' on the CPU_* symbol from the platform, mostly for consistency. The downside is that it gets a little messy for Integrator, but that's just one platform in the end. At some point, I think I got into circular dependencies when one CPU depended on another one being disabled, but I don't remember exactly what case that was. Arnd
On Wednesday 19 March 2014, Arnd Bergmann wrote: > On Wednesday 19 March 2014 20:49:47 Russell King - ARM Linux wrote: > > On Wed, Mar 19, 2014 at 08:29:41PM +0100, Arnd Bergmann wrote: > > > This adds a new Kconfig option for the Integrator platform to > > > choose between ARMv4/ARMv5 based CPUs and those based on ARMv6/ARMv7, > > > which is required because we cannot have both classes enabled in the > > > same kernel at compile time. > > > > Wouldn't it just be easier to make the older CPUs depend on > > !CPU_V6 && !CPU_V7 rather than trying to hack this for each platform? > > It's only two platforms: integrator and realview. Actually I took two > different approaches on these, and wanted to make up my mind first > which one is better. Any suggestion? > > I have a mild preference to always using 'select' on the CPU_* symbol > from the platform, mostly for consistency. The downside is that it > gets a little messy for Integrator, but that's just one platform in > the end. > > At some point, I think I got into circular dependencies when one CPU > depended on another one being disabled, but I don't remember exactly > what case that was. > Nevermind, I'll drop this patch for now, I just had an idea to do it better: Since Linus and I are trying to get Integrator and Realview moved over into ARCH_MULTIPLATFORM anyway, I'll defer the CPU selection question until that's done. Within ARCH_MULTIPLATFORM, we already want to deal with booting machines that are described entirely in DT and have no platform specific code, but we also want to be able to select the CPU types built into the kernel for them. For the v6/v6k/v7 selection, we can do this through the top-level multiplatform options we already have, as we don't expose the differences between the individual core implementations for the most part. We can potentially leave PJ4 and PJ4B as user-selectable. For the v4/v4t/v5 selection, I would allow any CPU to be manually enabled with a dependency on the ARCH_MULTI_V* option. Platforms that know what they have should obviously keep selecting the one they want. I would leave strongarm and xscale out of the selection, because I don't expect any platform based on those cores to ever become enabled for ARCH_MULTIPLATFORM, but all the others should be selectable. For the moment, I'll keep using my patches locally in order to keep randconfig building, and I'll follow up with a new patch after integrator and realview are part of multiplatform. That may take a while, but I'm sure we'll get there eventually. Arnd
On Thu, Mar 20, 2014 at 11:48 AM, Arnd Bergmann <arnd@arndb.de> wrote: > Nevermind, I'll drop this patch for now, I just had an idea to do it > better: Since Linus and I are trying to get Integrator and Realview > moved over into ARCH_MULTIPLATFORM anyway, I'll defer the CPU selection > question until that's done. Integrator is blocked by one single thing: <mach/memory.h> bus_to_virt/virt_to_bus. If we can get some consensus on Santosh's patches (or however we want to solve that) I'll do multiplatform for Integrator any day. Yours, Linus Walleij
On Tuesday 25 March 2014 21:34:21 Linus Walleij wrote: > On Thu, Mar 20, 2014 at 11:48 AM, Arnd Bergmann <arnd@arndb.de> wrote: > > > Nevermind, I'll drop this patch for now, I just had an idea to do it > > better: Since Linus and I are trying to get Integrator and Realview > > moved over into ARCH_MULTIPLATFORM anyway, I'll defer the CPU selection > > question until that's done. > > Integrator is blocked by one single thing: <mach/memory.h> > bus_to_virt/virt_to_bus. > > If we can get some consensus on Santosh's patches > (or however we want to solve that) I'll do multiplatform for > Integrator any day. Yes, I know. My point is that once the two are multiplatform, we wouldn't do the CPU selection patches like this anymore. Instead, I would just do config CPU_ARM920T bool "Support ARM920T processor" if ARCH_MULTI_V4T ... config CPU_ARM926T bool "Support ARM920T processor" if ARCH_MULTI_V5 ... ... In a multiplatform kernel, there is nothing wrong with just letting users turn on arbitrary combinations of CPUs as long as they are compatible at run-time (i.e. not v5+v7 combined). This will also let you run qemu images using the MACH_VIRT target and any CPU emulation. Of course, most platforms will still select the CPUs they actually use, but you can always add more. Arnd
On Wed, Mar 26, 2014 at 12:42 AM, Arnd Bergmann <arnd@arndb.de> wrote: > My point is that once the two are multiplatform, we wouldn't > do the CPU selection patches like this anymore. Instead, I would just do > > config CPU_ARM920T > bool "Support ARM920T processor" if ARCH_MULTI_V4T > ... > > config CPU_ARM926T > bool "Support ARM920T processor" if ARCH_MULTI_V5 > ... Ah I see, that's elegant. Yes let's go for this. Yours, Linus Walleij
diff --git a/arch/arm/mach-integrator/Kconfig b/arch/arm/mach-integrator/Kconfig index ba43321..8c797e77 100644 --- a/arch/arm/mach-integrator/Kconfig +++ b/arch/arm/mach-integrator/Kconfig @@ -2,6 +2,17 @@ if ARCH_INTEGRATOR menu "Integrator Options" +choice + prompt "CPU architecture level" + +config ARCH_INTEGRATOR_V4_V5 + bool "ARMv4 or ARMv5 CPUs" + +config ARCH_INTEGRATOR_V6_V7 + bool "ARMv6 or ARMv7 CPUs" + +endchoice + config ARCH_INTEGRATOR_AP bool "Support Integrator/AP and Integrator/PP2 platforms" select CLKSRC_MMIO diff --git a/arch/arm/mm/Kconfig b/arch/arm/mm/Kconfig index 8c94496..af76df4 100644 --- a/arch/arm/mm/Kconfig +++ b/arch/arm/mm/Kconfig @@ -21,7 +21,7 @@ config CPU_ARM7TDMI # ARM720T config CPU_ARM720T - bool "Support ARM720T processor" if ARCH_INTEGRATOR + bool "Support ARM720T processor" if ARCH_INTEGRATOR_V4_V5 select CPU_32v4T select CPU_ABRT_LV4T select CPU_CACHE_V4 @@ -39,7 +39,7 @@ config CPU_ARM720T # ARM740T config CPU_ARM740T - bool "Support ARM740T processor" if ARCH_INTEGRATOR + bool "Support ARM740T processor" if ARCH_INTEGRATOR_V4_V5 depends on !MMU select CPU_32v4T select CPU_ABRT_LV4T @@ -71,7 +71,7 @@ config CPU_ARM9TDMI # ARM920T config CPU_ARM920T - bool "Support ARM920T processor" if ARCH_INTEGRATOR + bool "Support ARM920T processor" if ARCH_INTEGRATOR_V4_V5 select CPU_32v4T select CPU_ABRT_EV4T select CPU_CACHE_V4WT @@ -89,7 +89,7 @@ config CPU_ARM920T # ARM922T config CPU_ARM922T - bool "Support ARM922T processor" if ARCH_INTEGRATOR + bool "Support ARM922T processor" if ARCH_INTEGRATOR_V4_V5 select CPU_32v4T select CPU_ABRT_EV4T select CPU_CACHE_V4WT @@ -127,7 +127,7 @@ config CPU_ARM925T # ARM926T config CPU_ARM926T - bool "Support ARM926T processor" if ARCH_INTEGRATOR + bool "Support ARM926T processor" if ARCH_INTEGRATOR_V4_V5 select CPU_32v5 select CPU_ABRT_EV5TJ select CPU_CACHE_VIVT @@ -163,7 +163,7 @@ config CPU_FA526 # ARM940T config CPU_ARM940T - bool "Support ARM940T processor" if ARCH_INTEGRATOR + bool "Support ARM940T processor" if ARCH_INTEGRATOR_V4_V5 depends on !MMU select CPU_32v4T select CPU_ABRT_NOMMU @@ -181,7 +181,7 @@ config CPU_ARM940T # ARM946E-S config CPU_ARM946E - bool "Support ARM946E-S processor" if ARCH_INTEGRATOR + bool "Support ARM946E-S processor" if ARCH_INTEGRATOR_V4_V5 depends on !MMU select CPU_32v5 select CPU_ABRT_NOMMU @@ -198,7 +198,7 @@ config CPU_ARM946E # ARM1020 - needs validating config CPU_ARM1020 - bool "Support ARM1020T (rev 0) processor" if ARCH_INTEGRATOR + bool "Support ARM1020T (rev 0) processor" if ARCH_INTEGRATOR_V4_V5 select CPU_32v5 select CPU_ABRT_EV4T select CPU_CACHE_V4WT @@ -216,7 +216,7 @@ config CPU_ARM1020 # ARM1020E - needs validating config CPU_ARM1020E - bool "Support ARM1020E processor" if ARCH_INTEGRATOR + bool "Support ARM1020E processor" if ARCH_INTEGRATOR_V4_V5 depends on n select CPU_32v5 select CPU_ABRT_EV4T @@ -229,7 +229,7 @@ config CPU_ARM1020E # ARM1022E config CPU_ARM1022 - bool "Support ARM1022E processor" if ARCH_INTEGRATOR + bool "Support ARM1022E processor" if ARCH_INTEGRATOR_V4_V5 select CPU_32v5 select CPU_ABRT_EV4T select CPU_CACHE_VIVT @@ -247,7 +247,7 @@ config CPU_ARM1022 # ARM1026EJ-S config CPU_ARM1026 - bool "Support ARM1026EJ-S processor" if ARCH_INTEGRATOR + bool "Support ARM1026EJ-S processor" if ARCH_INTEGRATOR_V4_V5 select CPU_32v5 select CPU_ABRT_EV5T # But need Jazelle, but EV5TJ ignores bit 10 select CPU_CACHE_VIVT @@ -358,7 +358,7 @@ config CPU_PJ4B # ARMv6 config CPU_V6 - bool "Support ARM V6 processor" if ARCH_INTEGRATOR + bool "Support ARM V6 processor" if ARCH_INTEGRATOR_V6_V7 select CPU_32v6 select CPU_ABRT_EV6 select CPU_CACHE_V6 @@ -371,7 +371,7 @@ config CPU_V6 # ARMv6k config CPU_V6K - bool "Support ARM V6K processor" if ARCH_INTEGRATOR + bool "Support ARM V6K processor" if ARCH_INTEGRATOR_V6_V7 select CPU_32v6 select CPU_32v6K select CPU_ABRT_EV6 @@ -385,7 +385,7 @@ config CPU_V6K # ARMv7 config CPU_V7 - bool "Support ARM V7 processor" if ARCH_INTEGRATOR + bool "Support ARM V7 processor" if ARCH_INTEGRATOR_V6_V7 select CPU_32v6K select CPU_32v7 select CPU_ABRT_EV7
This adds a new Kconfig option for the Integrator platform to choose between ARMv4/ARMv5 based CPUs and those based on ARMv6/ARMv7, which is required because we cannot have both classes enabled in the same kernel at compile time. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Cc: Russell King <linux@arm.linux.org.uk> Cc: Linus Walleij <linus.walleij@linaro.org> --- arch/arm/mach-integrator/Kconfig | 11 +++++++++++ arch/arm/mm/Kconfig | 28 ++++++++++++++-------------- 2 files changed, 25 insertions(+), 14 deletions(-)