| Message ID | 1437073441-11321-1-git-send-email-abrodkin@synopsys.com |
|---|---|
| State | Changes Requested |
| Headers | show |
Dear Alexey Brodkin, On Thu, 16 Jul 2015 22:04:01 +0300, Alexey Brodkin wrote: > +choice > + prompt "MMU Page Size" > + default BR2_arc_page_size_8k > + help > + MMU starting from version 3 (could be found in ARC 770) and now > + version 4 (could be found in ARC HS38) allows selection of page > + size during ASIC design creation. And it's important to build Remove the "And". > + a toolchain with page size setting that matches hardware. "with a page size matching the hardware configuration" > + Otherwise user-space applications will fail on execution due to "will fail at runtime" > + unexpected data layout/alignment. What is the impact for people using external toolchains? > + > +config BR2_arc_page_size_4k Can you use BR2_ARC_PAGE_SIZE_4K instead? I know the BR2_arc option is lower-case, but for most architectures options are upper-case, even if the core selection is lower-case. I think lower-case options is more an accident of the past rather than a real policy. > + bool "4KB" > + depends on BR2_arc770d || BR2_archs38 > + > +config BR2_arc_page_size_8k > + bool "8KB" > + > +config BR2_arc_page_size_16k > + bool "16KB" > + depends on BR2_arc770d || BR2_archs38 Can you quickly comment on why 4 KB / 16 KB have dependencies on specific ARC cores and not 8 KB ? Can you respin with those changes? Thanks! Thomas
On 07/16/15 21:04, Alexey Brodkin wrote: > Modern ARC cores (those sporting MMU of version 3 and 4) allow selection > of different page sizes (4, 8 or 16 kB) during ASIC design creation. > And it's important to build a toolchain with page size setting that matches > hardware. > > Otherwise user-space applications will fail on execution due to > unexpected data layout/alignment etc. > > Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> > c: Anton Kolesov <akolesov@synopsys.com> > Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> > --- > arch/Config.in.arc | 30 ++++++++++++++++++++++++++++++ > package/uclibc/uclibc.mk | 8 ++++++++ > 2 files changed, 38 insertions(+) > > diff --git a/arch/Config.in.arc b/arch/Config.in.arc > index b48a90f..e960eb8 100644 > --- a/arch/Config.in.arc > +++ b/arch/Config.in.arc > @@ -40,3 +40,33 @@ config BR2_GCC_TARGET_CPU > default "arc700" if BR2_arc750d > default "arc700" if BR2_arc770d > default "archs" if BR2_archs38 > + > +choice > + prompt "MMU Page Size" It is not really current policy, but wouldn't it make more sense to do prompt "MMU Page Size" if BR2_arc770d || BR2_archs38 ? (i.e., only show it when there's anything to choose). Also perhaps it makes sense to add a new symbol BR2_ARC_SUPPORTS_PAGE_SIZE_SELECTION or similar instead of specifying the individual processors. Regards, Arnout > + default BR2_arc_page_size_8k > + help > + MMU starting from version 3 (could be found in ARC 770) and now > + version 4 (could be found in ARC HS38) allows selection of page > + size during ASIC design creation. And it's important to build > + a toolchain with page size setting that matches hardware. > + Otherwise user-space applications will fail on execution due to > + unexpected data layout/alignment. > + > +config BR2_arc_page_size_4k > + bool "4KB" > + depends on BR2_arc770d || BR2_archs38 > + > +config BR2_arc_page_size_8k > + bool "8KB" > + > +config BR2_arc_page_size_16k > + bool "16KB" > + depends on BR2_arc770d || BR2_archs38 [snip]
Arnout, On Fri, 17 Jul 2015 00:40:20 +0200, Arnout Vandecappelle wrote: > > +choice > > + prompt "MMU Page Size" > > It is not really current policy, but wouldn't it make more sense to do > > prompt "MMU Page Size" if BR2_arc770d || BR2_archs38 Why? In the patch submitted by Alexey, the 8K option is available for all cores. Thomas
Hi Thomas, Arnout, On Fri, 2015-07-17 at 09:59 +0200, Thomas Petazzoni wrote: > Arnout, > > On Fri, 17 Jul 2015 00:40:20 +0200, Arnout Vandecappelle wrote: > > > > +choice > > > + prompt "MMU Page Size" > > > > It is not really current policy, but wouldn't it make more sense to do > > > > prompt "MMU Page Size" if BR2_arc770d || BR2_archs38 > > Why? In the patch submitted by Alexey, the 8K option is available for > all cores. Indeed there's no reason to select page size for MMUv2 (read ARC 750D), but IMHO it's good to let user know what's current page size. Because software built for ARC 750D will run perfectly fine on ARC770D if it has the same page size (and by default it is 8k). That's why I decided to leave a "Page Size" entry in configuration utility even though it could not be modified for ARC 750D. -Alexey
Hi Thomas, On Thu, 2015-07-16 at 23:25 +0200, Thomas Petazzoni wrote: > Dear Alexey Brodkin, > > On Thu, 16 Jul 2015 22:04:01 +0300, Alexey Brodkin wrote: > > > +choice > > + prompt "MMU Page Size" > > + default BR2_arc_page_size_8k > > + help > > + MMU starting from version 3 (could be found in ARC 770) and now > > + version 4 (could be found in ARC HS38) allows selection of page > > + size during ASIC design creation. And it's important to build > > Remove the "And". > > > + a toolchain with page size setting that matches hardware. > > "with a page size matching the hardware configuration" > > > + Otherwise user-space applications will fail on execution due to > > "will fail at runtime" Thanks for pointing to that. > > + unexpected data layout/alignment. > > What is the impact for people using external toolchains? Well people have to use toolchain which page size matches HW. That means you need to know which value is set in both toolchain and HW. By default in either substances 8k is used and most of the time people will use it. Still even in case of external toolchain we nay check for PAGE_SHIFT value in "sysroot/usr/include/bits/uClibc_page.h". PAGE_SHIFT=12 -> PAGE_SIZE=4k PAGE_SHIFT=13 -> PAGE_SIZE=8k (default) PAGE_SHIFT=14 -> PAGE_SIZE=16k > > + > > +config BR2_arc_page_size_4k > > Can you use BR2_ARC_PAGE_SIZE_4K instead? I know the BR2_arc option is > lower-case, but for most architectures options are upper-case, even if > the core selection is lower-case. I think lower-case options is more an > accident of the past rather than a real policy. OK, will do. > > + bool "4KB" > > + depends on BR2_arc770d || BR2_archs38 > > + > > +config BR2_arc_page_size_8k > > + bool "8KB" > > + > > +config BR2_arc_page_size_16k > > + bool "16KB" > > + depends on BR2_arc770d || BR2_archs38 > > Can you quickly comment on why 4 KB / 16 KB have dependencies on > specific ARC cores and not 8 KB ? 8K page was the only option on earlier ARC cores like ARC 750D. Starting from ARC 770D it's possible to select page size from 3 options: 4, 8 and 16k. But still 8k is its default value and most often that's what people use. Do you want that comment > Can you respin with those changes? Sure, will do shortly.\ -Alexey
diff --git a/arch/Config.in.arc b/arch/Config.in.arc index b48a90f..e960eb8 100644 --- a/arch/Config.in.arc +++ b/arch/Config.in.arc @@ -40,3 +40,33 @@ config BR2_GCC_TARGET_CPU default "arc700" if BR2_arc750d default "arc700" if BR2_arc770d default "archs" if BR2_archs38 + +choice + prompt "MMU Page Size" + default BR2_arc_page_size_8k + help + MMU starting from version 3 (could be found in ARC 770) and now + version 4 (could be found in ARC HS38) allows selection of page + size during ASIC design creation. And it's important to build + a toolchain with page size setting that matches hardware. + Otherwise user-space applications will fail on execution due to + unexpected data layout/alignment. + +config BR2_arc_page_size_4k + bool "4KB" + depends on BR2_arc770d || BR2_archs38 + +config BR2_arc_page_size_8k + bool "8KB" + +config BR2_arc_page_size_16k + bool "16KB" + depends on BR2_arc770d || BR2_archs38 + +endchoice + +config BR2_ARC_PAGE_SIZE + string + default "4K" if BR2_arc_page_size_4k + default "8K" if BR2_arc_page_size_8k + default "16K" if BR2_arc_page_size_16k diff --git a/package/uclibc/uclibc.mk b/package/uclibc/uclibc.mk index 9dfafad..a2ba230 100644 --- a/package/uclibc/uclibc.mk +++ b/package/uclibc/uclibc.mk @@ -70,6 +70,13 @@ UCLIBC_ARC_TYPE = CONFIG_$(call qstrip,$(BR2_UCLIBC_ARC_TYPE)) define UCLIBC_ARC_TYPE_CONFIG $(call KCONFIG_ENABLE_OPT,$(UCLIBC_ARC_TYPE),$(@D)/.config) endef + +UCLIBC_ARC_PAGE_SIZE = CONFIG_ARC_PAGE_SIZE_$(call qstrip,$(BR2_ARC_PAGE_SIZE)) +define UCLIBC_ARC_PAGE_SIZE_CONFIG + $(SED) '/CONFIG_ARC_PAGE_SIZE_*/d' $(@D)/.config + $(call KCONFIG_ENABLE_OPT,$(UCLIBC_ARC_PAGE_SIZE),$(@D)/.config) +endef + endif # arc # @@ -367,6 +374,7 @@ define UCLIBC_KCONFIG_FIXUP_CMDS $(call KCONFIG_SET_OPT,SHARED_LIB_LOADER_PREFIX,"/lib",$(@D)/.config) $(UCLIBC_MMU_CONFIG) $(UCLIBC_ARC_TYPE_CONFIG) + $(UCLIBC_ARC_PAGE_SIZE_CONFIG) $(UCLIBC_ARM_ABI_CONFIG) $(UCLIBC_ARM_BX_CONFIG) $(UCLIBC_MIPS_ABI_CONFIG)
Modern ARC cores (those sporting MMU of version 3 and 4) allow selection of different page sizes (4, 8 or 16 kB) during ASIC design creation. And it's important to build a toolchain with page size setting that matches hardware. Otherwise user-space applications will fail on execution due to unexpected data layout/alignment etc. Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com> c: Anton Kolesov <akolesov@synopsys.com> Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> --- arch/Config.in.arc | 30 ++++++++++++++++++++++++++++++ package/uclibc/uclibc.mk | 8 ++++++++ 2 files changed, 38 insertions(+)