| Message ID | 1330004385-22502-3-git-send-email-aneesh@ti.com |
|---|---|
| State | Superseded |
| Headers | show |
On Thursday 23 February 2012 08:39:43 Aneesh V wrote: > --- a/arch/arm/config.mk > +++ b/arch/arm/config.mk > > -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be > -mthumb: +# Choose between ARM/Thumb instruction sets > +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) > +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ > + $(call cc-option,-marm,)\ > + $(call cc-option,-mno-thumb-interwork,)\ > + ) > +else > PF_CPPFLAGS_ARM := $(call cc-option,-marm,) > +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) this 2nd part is no good. "+=" is not the same thing as ":=". might be simpler to do: PF_CPPFLAGS_MARM := $(call cc-option,-marm) PF_CPPFLAGS_THUMB := $(call cc-option,-mthumb -mthumb-interwork) PF_CPPFLAGS_NO_THUMB := $(call cc-option,-mno-thumb-interwork) ifeq ($(CONFIG_SYS_THUMB_BUILD),y) PF_CPPFLAGS_ARM = $(PF_CPPFLAGS_THUMB) else PF_CPPFLAGS_ARM = $(PF_CPPFLAGS_MARM) $(PF_CPPFLAGS_NO_THUMB) endif -mike
On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: > On Thursday 23 February 2012 08:39:43 Aneesh V wrote: >> --- a/arch/arm/config.mk >> +++ b/arch/arm/config.mk >> >> -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be >> -mthumb: +# Choose between ARM/Thumb instruction sets >> +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) >> +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ >> + $(call cc-option,-marm,)\ >> + $(call cc-option,-mno-thumb-interwork,)\ >> + ) >> +else >> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) >> +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) > > this 2nd part is no good. "+=" is not the same thing as ":=". I don't understand the difference. '+=' is done after ':=' right? > > might be simpler to do: > PF_CPPFLAGS_MARM := $(call cc-option,-marm) > PF_CPPFLAGS_THUMB := $(call cc-option,-mthumb -mthumb-interwork) > PF_CPPFLAGS_NO_THUMB := $(call cc-option,-mno-thumb-interwork) > > ifeq ($(CONFIG_SYS_THUMB_BUILD),y) > PF_CPPFLAGS_ARM = $(PF_CPPFLAGS_THUMB) > else > PF_CPPFLAGS_ARM = $(PF_CPPFLAGS_MARM) $(PF_CPPFLAGS_NO_THUMB) > endif > -mike Are you trying to avoid all '+='. If so, why?
On Thu, Feb 23, 2012 at 10:58:36PM +0530, Aneesh V wrote: > On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: > >On Thursday 23 February 2012 08:39:43 Aneesh V wrote: > >>--- a/arch/arm/config.mk > >>+++ b/arch/arm/config.mk > >> > >>-# Explicitly specifiy 32-bit ARM ISA since toolchain default can be > >>-mthumb: +# Choose between ARM/Thumb instruction sets > >>+ifeq ($(CONFIG_SYS_THUMB_BUILD),y) > >>+PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ > >>+ $(call cc-option,-marm,)\ > >>+ $(call cc-option,-mno-thumb-interwork,)\ > >>+ ) > >>+else > >> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) > >>+PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) > > > >this 2nd part is no good. "+=" is not the same thing as ":=". > > I don't understand the difference. '+=' is done after ':=' right? '+=' is evaluated every file we build, ':=' is evaluated once. We use the latter to keep build times down.
On Thursday 23 February 2012 11:04 PM, Tom Rini wrote: > On Thu, Feb 23, 2012 at 10:58:36PM +0530, Aneesh V wrote: >> On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: >>> On Thursday 23 February 2012 08:39:43 Aneesh V wrote: >>>> --- a/arch/arm/config.mk >>>> +++ b/arch/arm/config.mk >>>> >>>> -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be >>>> -mthumb: +# Choose between ARM/Thumb instruction sets >>>> +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) >>>> +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ >>>> + $(call cc-option,-marm,)\ >>>> + $(call cc-option,-mno-thumb-interwork,)\ >>>> + ) >>>> +else >>>> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) >>>> +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) >>> >>> this 2nd part is no good. "+=" is not the same thing as ":=". >> >> I don't understand the difference. '+=' is done after ':=' right? > > '+=' is evaluated every file we build, ':=' is evaluated once. We use > the latter to keep build times down. > Ok. so, are we trying to reduce the number of "+=", right? Thanks for clarifying. br, Aneesh
On Thu, Feb 23, 2012 at 11:19:59PM +0530, Aneesh V wrote: > On Thursday 23 February 2012 11:04 PM, Tom Rini wrote: > >On Thu, Feb 23, 2012 at 10:58:36PM +0530, Aneesh V wrote: > >>On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: > >>>On Thursday 23 February 2012 08:39:43 Aneesh V wrote: > >>>>--- a/arch/arm/config.mk > >>>>+++ b/arch/arm/config.mk > >>>> > >>>>-# Explicitly specifiy 32-bit ARM ISA since toolchain default can be > >>>>-mthumb: +# Choose between ARM/Thumb instruction sets > >>>>+ifeq ($(CONFIG_SYS_THUMB_BUILD),y) > >>>>+PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ > >>>>+ $(call cc-option,-marm,)\ > >>>>+ $(call cc-option,-mno-thumb-interwork,)\ > >>>>+ ) > >>>>+else > >>>> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) > >>>>+PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) > >>> > >>>this 2nd part is no good. "+=" is not the same thing as ":=". > >> > >>I don't understand the difference. '+=' is done after ':=' right? > > > >'+=' is evaluated every file we build, ':=' is evaluated once. We use > >the latter to keep build times down. > > > > Ok. so, are we trying to reduce the number of "+=", right? Yes, it should already be at or near 0 uses.
On Thursday 23 February 2012 12:28:36 Aneesh V wrote: > On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: > > On Thursday 23 February 2012 08:39:43 Aneesh V wrote: > >> --- a/arch/arm/config.mk > >> +++ b/arch/arm/config.mk > >> > >> -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be > >> -mthumb: +# Choose between ARM/Thumb instruction sets > >> +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) > >> +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ > >> + $(call cc-option,-marm,)\ > >> + $(call cc-option,-mno-thumb-interwork,)\ > >> + ) > >> +else > >> > >> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) > >> > >> +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) > > > > this 2nd part is no good. "+=" is not the same thing as ":=". > > I don't understand the difference. '+=' is done after ':=' right? > > > might be simpler to do: > > PF_CPPFLAGS_MARM := $(call cc-option,-marm) > > PF_CPPFLAGS_THUMB := $(call cc-option,-mthumb -mthumb-interwork) > > PF_CPPFLAGS_NO_THUMB := $(call cc-option,-mno-thumb-interwork) > > > > ifeq ($(CONFIG_SYS_THUMB_BUILD),y) > > PF_CPPFLAGS_ARM = $(PF_CPPFLAGS_THUMB) > > else > > PF_CPPFLAGS_ARM = $(PF_CPPFLAGS_MARM) $(PF_CPPFLAGS_NO_THUMB) > > endif > > Are you trying to avoid all '+='. If so, why? "+=" does delayed evaluation and is the whole reason we started using ":=" in makefiles for *computed* values when you do: FOO := $(call cc-option,-marm) you're storing the result of the computation in $(FOO) if you do: FOO += $(call cc-option,-marm) you're appending "$(call cc-option,-marm)" to $(FOO) and that won't actually get computed until $(FOO) gets used so if you append $(call ...) to $(CPPFLAGS), then you end up doing the cc- option computation every time you compile a file that uses $(CPPFLAGS) -mike
On Thursday 23 February 2012 12:49:59 Aneesh V wrote: > On Thursday 23 February 2012 11:04 PM, Tom Rini wrote: > > On Thu, Feb 23, 2012 at 10:58:36PM +0530, Aneesh V wrote: > >> On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: > >>> On Thursday 23 February 2012 08:39:43 Aneesh V wrote: > >>>> --- a/arch/arm/config.mk > >>>> +++ b/arch/arm/config.mk > >>>> > >>>> -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be > >>>> -mthumb: +# Choose between ARM/Thumb instruction sets > >>>> +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) > >>>> +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ > >>>> + $(call cc-option,-marm,)\ > >>>> + $(call cc-option,-mno-thumb-interwork,)\ > >>>> + ) > >>>> +else > >>>> > >>>> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) > >>>> > >>>> +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) > >>> > >>> this 2nd part is no good. "+=" is not the same thing as ":=". > >> > >> I don't understand the difference. '+=' is done after ':=' right? > > > > '+=' is evaluated every file we build, ':=' is evaluated once. We use > > the latter to keep build times down. > > Ok. so, are we trying to reduce the number of "+=", right? for things that require computation, yes. if it's just string values or other variables, then it doesn't matter and avoiding ":=" is preferred. -mike
On Thursday 23 February 2012 11:21 PM, Tom Rini wrote: > On Thu, Feb 23, 2012 at 11:19:59PM +0530, Aneesh V wrote: >> On Thursday 23 February 2012 11:04 PM, Tom Rini wrote: >>> On Thu, Feb 23, 2012 at 10:58:36PM +0530, Aneesh V wrote: >>>> On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: >>>>> On Thursday 23 February 2012 08:39:43 Aneesh V wrote: >>>>>> --- a/arch/arm/config.mk >>>>>> +++ b/arch/arm/config.mk >>>>>> >>>>>> -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be >>>>>> -mthumb: +# Choose between ARM/Thumb instruction sets >>>>>> +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) >>>>>> +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ >>>>>> + $(call cc-option,-marm,)\ >>>>>> + $(call cc-option,-mno-thumb-interwork,)\ >>>>>> + ) >>>>>> +else >>>>>> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) >>>>>> +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) >>>>> >>>>> this 2nd part is no good. "+=" is not the same thing as ":=". >>>> >>>> I don't understand the difference. '+=' is done after ':=' right? >>> >>> '+=' is evaluated every file we build, ':=' is evaluated once. We use >>> the latter to keep build times down. >>> >> >> Ok. so, are we trying to reduce the number of "+=", right? > > Yes, it should already be at or near 0 uses. We need at least one for finally appending to the exported variable, right. So, looks like one += for adding '-mthumb -mthumb-interwork' together is better than having one each for the two options? Is that the logic?
On Thursday 23 February 2012 11:34 PM, Mike Frysinger wrote: > On Thursday 23 February 2012 12:28:36 Aneesh V wrote: >> On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: >>> On Thursday 23 February 2012 08:39:43 Aneesh V wrote: >>>> --- a/arch/arm/config.mk >>>> +++ b/arch/arm/config.mk >>>> >>>> -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be >>>> -mthumb: +# Choose between ARM/Thumb instruction sets >>>> +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) >>>> +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ >>>> + $(call cc-option,-marm,)\ >>>> + $(call cc-option,-mno-thumb-interwork,)\ >>>> + ) >>>> +else >>>> >>>> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) >>>> >>>> +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) >>> >>> this 2nd part is no good. "+=" is not the same thing as ":=". >> >> I don't understand the difference. '+=' is done after ':=' right? >> >>> might be simpler to do: >>> PF_CPPFLAGS_MARM := $(call cc-option,-marm) >>> PF_CPPFLAGS_THUMB := $(call cc-option,-mthumb -mthumb-interwork) >>> PF_CPPFLAGS_NO_THUMB := $(call cc-option,-mno-thumb-interwork) >>> >>> ifeq ($(CONFIG_SYS_THUMB_BUILD),y) >>> PF_CPPFLAGS_ARM = $(PF_CPPFLAGS_THUMB) >>> else >>> PF_CPPFLAGS_ARM = $(PF_CPPFLAGS_MARM) $(PF_CPPFLAGS_NO_THUMB) >>> endif >> >> Are you trying to avoid all '+='. If so, why? > > "+=" does delayed evaluation and is the whole reason we started using ":=" in > makefiles for *computed* values > > when you do: > FOO := $(call cc-option,-marm) > you're storing the result of the computation in $(FOO) > > if you do: > FOO += $(call cc-option,-marm) > you're appending "$(call cc-option,-marm)" to $(FOO) and that won't actually > get computed until $(FOO) gets used > > so if you append $(call ...) to $(CPPFLAGS), then you end up doing the cc- > option computation every time you compile a file that uses $(CPPFLAGS) Get it. Thanks for explaining. I missed the computation part. br, Aneesh > -mike
On Thursday 23 February 2012 11:39 PM, Aneesh V wrote: > On Thursday 23 February 2012 11:21 PM, Tom Rini wrote: >> On Thu, Feb 23, 2012 at 11:19:59PM +0530, Aneesh V wrote: >>> On Thursday 23 February 2012 11:04 PM, Tom Rini wrote: >>>> On Thu, Feb 23, 2012 at 10:58:36PM +0530, Aneesh V wrote: >>>>> On Thursday 23 February 2012 08:27 PM, Mike Frysinger wrote: >>>>>> On Thursday 23 February 2012 08:39:43 Aneesh V wrote: >>>>>>> --- a/arch/arm/config.mk >>>>>>> +++ b/arch/arm/config.mk >>>>>>> >>>>>>> -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be >>>>>>> -mthumb: +# Choose between ARM/Thumb instruction sets >>>>>>> +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) >>>>>>> +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ >>>>>>> + $(call cc-option,-marm,)\ >>>>>>> + $(call cc-option,-mno-thumb-interwork,)\ >>>>>>> + ) >>>>>>> +else >>>>>>> PF_CPPFLAGS_ARM := $(call cc-option,-marm,) >>>>>>> +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) >>>>>> >>>>>> this 2nd part is no good. "+=" is not the same thing as ":=". >>>>> >>>>> I don't understand the difference. '+=' is done after ':=' right? >>>> >>>> '+=' is evaluated every file we build, ':=' is evaluated once. We use >>>> the latter to keep build times down. >>>> >>> >>> Ok. so, are we trying to reduce the number of "+=", right? >> >> Yes, it should already be at or near 0 uses. > > We need at least one for finally appending to the exported variable, > right. So, looks like one += for adding '-mthumb -mthumb-interwork' > together is better than having one each for the two options? Is that > the logic? > Please ignore this question. It's clear to me now with Mike's latest explanation. Thanks.
diff --git a/README b/README index eba6378..1f4e2e8 100644 --- a/README +++ b/README @@ -426,6 +426,14 @@ The following options need to be configured: Select high exception vectors of the ARM core, e.g., do not clear the V bit of the c1 register of CP15. + CONFIG_SYS_THUMB_BUILD + + Use this flag to build U-Boot using the Thumb instruction + set for ARM architectures. Thumb instruction set provides + better code density. For ARM architectures that support + Thumb2 this flag will result in Thumb2 code generated by + GCC. + - Linux Kernel Interface: CONFIG_CLOCKS_IN_MHZ diff --git a/arch/arm/config.mk b/arch/arm/config.mk index 45f9dca..de9aa53 100644 --- a/arch/arm/config.mk +++ b/arch/arm/config.mk @@ -33,25 +33,33 @@ endif PLATFORM_CPPFLAGS += -DCONFIG_ARM -D__ARM__ -# Explicitly specifiy 32-bit ARM ISA since toolchain default can be -mthumb: +# Choose between ARM/Thumb instruction sets +ifeq ($(CONFIG_SYS_THUMB_BUILD),y) +PF_CPPFLAGS_ARM := $(call cc-option, -mthumb -mthumb-interwork,\ + $(call cc-option,-marm,)\ + $(call cc-option,-mno-thumb-interwork,)\ + ) +else PF_CPPFLAGS_ARM := $(call cc-option,-marm,) +PF_CPPFLAGS_ARM += $(call cc-option,-mno-thumb-interwork,) +endif # Try if EABI is supported, else fall back to old API, # i. e. for example: # - with ELDK 4.2 (EABI supported), use: -# -mabi=aapcs-linux -mno-thumb-interwork +# -mabi=aapcs-linux # - with ELDK 4.1 (gcc 4.x, no EABI), use: -# -mabi=apcs-gnu -mno-thumb-interwork +# -mabi=apcs-gnu # - with ELDK 3.1 (gcc 3.x), use: -# -mapcs-32 -mno-thumb-interwork +# -mapcs-32 PF_CPPFLAGS_ABI := $(call cc-option,\ - -mabi=aapcs-linux -mno-thumb-interwork,\ + -mabi=aapcs-linux,\ $(call cc-option,\ -mapcs-32,\ $(call cc-option,\ -mabi=apcs-gnu,\ )\ - ) $(call cc-option,-mno-thumb-interwork,)\ + )\ ) PLATFORM_CPPFLAGS += $(PF_CPPFLAGS_ARM) $(PF_CPPFLAGS_ABI)
Enable Thumb build and ARM-Thumb interworking based on the new config flag CONFIG_SYS_THUMB_BUILD Signed-off-by: Aneesh V <aneesh@ti.com> --- Changes from RFC to V1: - Fixed review comments from Tom Rini <trini@ti.com> Changes from V1 to V2: - None --- README | 8 ++++++++ arch/arm/config.mk | 20 ++++++++++++++------ 2 files changed, 22 insertions(+), 6 deletions(-)