* [Buildroot] [PATCH] arch: Set max/common-page-size for libgcc & libstdc++
@ 2024-01-03 10:23 Alexey Brodkin via buildroot
2024-01-04 21:19 ` Thomas Petazzoni via buildroot
0 siblings, 1 reply; 6+ messages in thread
From: Alexey Brodkin via buildroot @ 2024-01-03 10:23 UTC (permalink / raw)
To: buildroot
Cc: Vladimir Isaev, Pavel Kozlov, Alexey Brodkin, Thomas Petazzoni,
Yann E . MORIN
With [1], [2] & [3] we made sure Buildroot packages get built with
proper MMU page size assumed. This was done nicely through insertion of
required flags into the toolchain wrapper so that there's no need to
pass these flags to each and every package separately - toolchain
wrapper used for real building has all set internally and so proper
flags are impleicitly used.
But there's yet another corner case which is not handled that way -
these are binaries or rather libraries which are being used as a part of
GCC compilation: libgcc_s.so.1 and libstdc++.so.
And so to make sure both the libraries get built properly we need to set
TARGET_CFLAGS (cures libgcc_s.so) & TARGET_LDFLAGS (cures libstdc++.so).
In case of ARM by defaut 64 KiB page size seems to be used, as w/o that
patch I see the following for BR2_ARM64_PAGE_SIZE_4K=y:
--------------------------->8----------------------------
$ ./output/host/bin/aarch64-linux-readelf -l ./output/target/lib/libgcc_s.so.1
Elf file type is DYN (Shared object file)
Entry point 0x0
There are 6 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000013d1c 0x0000000000013d1c R E 0x10000
LOAD 0x000000000001fd98 0x000000000002fd98 0x000000000002fd98
0x0000000000000438 0x00000000000005c8 RW 0x10000
DYNAMIC 0x000000000001fdb8 0x000000000002fdb8 0x000000000002fdb8
0x0000000000000200 0x0000000000000200 RW 0x8
$ ./output/host/bin/aarch64-linux-readelf -l ./output/target/usr/lib/libstdc++.so.6.0.32
Elf file type is DYN (Shared object file)
Entry point 0x0
There are 7 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x00000000001d3462 0x00000000001d3462 R E 0x10000
LOAD 0x00000000001d5760 0x00000000001e5760 0x00000000001e5760
0x000000000000e528 0x0000000000012de8 RW 0x10000
DYNAMIC 0x00000000001deef0 0x00000000001eeef0 0x00000000001eeef0
0x0000000000000240 0x0000000000000240 RW 0x8
--------------------------->8----------------------------
Note alignment of 0x10000 in sections marked for loading.
And with the patch applied we get expected alignment of 0x1000 (4 KiB):
--------------------------->8----------------------------
$ ./output/host/bin/aarch64-linux-readelf -l ./output/target/lib/libgcc_s.so.1
Elf file type is DYN (Shared object file)
Entry point 0x0
There are 6 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x0000000000013d1c 0x0000000000013d1c R E 0x1000
LOAD 0x0000000000013d98 0x0000000000014d98 0x0000000000014d98
0x0000000000000438 0x00000000000005c8 RW 0x1000
DYNAMIC 0x0000000000013db8 0x0000000000014db8 0x0000000000014db8
0x0000000000000200 0x0000000000000200 RW 0x8
$ ./output/host/bin/aarch64-linux-readelf -l ./output/target/usr/lib/libstdc++.so.6.0.32
Elf file type is DYN (Shared object file)
Entry point 0x0
There are 7 program headers, starting at offset 64
Program Headers:
Type Offset VirtAddr PhysAddr
FileSiz MemSiz Flags Align
LOAD 0x0000000000000000 0x0000000000000000 0x0000000000000000
0x00000000001d3462 0x00000000001d3462 R E 0x1000
LOAD 0x00000000001d3760 0x00000000001d4760 0x00000000001d4760
0x000000000000e528 0x0000000000012de8 RW 0x1000
DYNAMIC 0x00000000001dcef0 0x00000000001ddef0 0x00000000001ddef0
0x0000000000000240 0x0000000000000240 RW 0x8
--------------------------->8----------------------------
I would agree that it gets more and more ugly, but so far I cannot see
any more elegant solution. So if there're suggestions how to improve,
let's discuss.
[1] https://git.buildroot.net/buildroot/commit/?id=3cc2c6d19ab2e1bb4634f26f9318da9b07df5fff
[2] https://git.buildroot.net/buildroot/commit/?id=dcb74db89e74e512e36b32cea6f574a1a1ca84c4
[3] https://git.buildroot.net/buildroot/commit/?id=5e52c28397b79f8c4c99552217cbe95202166626
Signed-off-by: Alexey Brodkin <abrodkin@synopsys.com>
Signed-off-by: Vladimir Isaev <VVIsaev@gmail.com>
Signed-off-by: Pavel Kozlov <kozlov@synopsys.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Arnout Vandecappelle <arnout@mind.be>
---
arch/arch.mk | 8 ++++++++
package/gcc/gcc.mk | 2 ++
2 files changed, 10 insertions(+)
diff --git a/arch/arch.mk b/arch/arch.mk
index 2e737b92ac..23733eb199 100644
--- a/arch/arch.mk
+++ b/arch/arch.mk
@@ -21,12 +21,20 @@ GCC_TARGET_MODE := $(call qstrip,$(BR2_GCC_TARGET_MODE))
# Explicitly set LD's "max-page-size" instead of relying on some defaults
ifeq ($(BR2_ARC_PAGE_SIZE_4K)$(BR2_ARM64_PAGE_SIZE_4K),y)
ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
+TARGET_CFLAGS += -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
+TARGET_LDFLAGS += -Wl,-z,max-page-size=4096 -Wl,-z,common-page-size=4096
else ifeq ($(BR2_ARC_PAGE_SIZE_8K),y)
ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=8192 -Wl,-z,common-page-size=8192
+TARGET_CFLAGS += -Wl,-z,max-page-size=8192 -Wl,-z,common-page-size=8192
+TARGET_LDFLAGS += -Wl,-z,max-page-size=8192 -Wl,-z,common-page-size=8192
else ifeq ($(BR2_ARC_PAGE_SIZE_16K),y)
ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=16384 -Wl,-z,common-page-size=16384
+TARGET_CFLAGS += -Wl,-z,max-page-size=16384 -Wl,-z,common-page-size=16384
+TARGET_LDFLAGS += -Wl,-z,max-page-size=16384 -Wl,-z,common-page-size=16384
else ifeq ($(BR2_ARM64_PAGE_SIZE_64K),y)
ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=65536 -Wl,-z,common-page-size=65536
+TARGET_CFLAGS += -Wl,-z,max-page-size=65536 -Wl,-z,common-page-size=65536
+TARGET_LDFLAGS += -Wl,-z,max-page-size=65536 -Wl,-z,common-page-size=65536
endif
# Include any architecture specific makefiles.
diff --git a/package/gcc/gcc.mk b/package/gcc/gcc.mk
index 93bc46643c..d9a2164c74 100644
--- a/package/gcc/gcc.mk
+++ b/package/gcc/gcc.mk
@@ -100,6 +100,7 @@ HOST_GCC_COMMON_MAKE_OPTS = \
GCC_COMMON_TARGET_CFLAGS = $(TARGET_CFLAGS)
GCC_COMMON_TARGET_CXXFLAGS = $(TARGET_CXXFLAGS)
+GCC_COMMON_TARGET_LDFLAGS = $(TARGET_LDFLAGS)
# used to fix ../../../../libsanitizer/libbacktrace/../../libbacktrace/elf.c:772:21: error: 'st.st_mode' may be used uninitialized in this function [-Werror=maybe-uninitialized]
ifeq ($(BR2_ENABLE_DEBUG),y)
@@ -115,6 +116,7 @@ endif
# Propagate options used for target software building to GCC target libs
HOST_GCC_COMMON_CONF_ENV += CFLAGS_FOR_TARGET="$(GCC_COMMON_TARGET_CFLAGS)"
HOST_GCC_COMMON_CONF_ENV += CXXFLAGS_FOR_TARGET="$(GCC_COMMON_TARGET_CXXFLAGS)"
+HOST_GCC_COMMON_CONF_ENV += LDFLAGS_FOR_TARGET="$(GCC_COMMON_TARGET_LDFLAGS)"
HOST_GCC_COMMON_CONF_ENV += AR_FOR_TARGET=gcc-ar NM_FOR_TARGET=gcc-nm RANLIB_FOR_TARGET=gcc-ranlib
# libitm needs sparc V9+
--
2.31.1
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^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [Buildroot] [PATCH] arch: Set max/common-page-size for libgcc & libstdc++
2024-01-03 10:23 [Buildroot] [PATCH] arch: Set max/common-page-size for libgcc & libstdc++ Alexey Brodkin via buildroot
@ 2024-01-04 21:19 ` Thomas Petazzoni via buildroot
2024-01-04 21:34 ` Yann E. MORIN
0 siblings, 1 reply; 6+ messages in thread
From: Thomas Petazzoni via buildroot @ 2024-01-04 21:19 UTC (permalink / raw)
To: Alexey Brodkin via buildroot
Cc: Alexey Brodkin, Yann E . MORIN, Vladimir Isaev, Pavel Kozlov
Hello Alexey,
Thanks for the patch. See below some comments.
On Wed, 3 Jan 2024 02:23:11 -0800
Alexey Brodkin via buildroot <buildroot@buildroot.org> wrote:
> I would agree that it gets more and more ugly, but so far I cannot see
> any more elegant solution. So if there're suggestions how to improve,
> let's discuss.
Indeed, it's not super great as you realized yourself. Also, I believe
it's not the first time we identify a discrepancy in CFLAGS that are in
the wrapper, but that we forget to pass when building gcc/libc. See
your own commit d2ae7eb2a24c9033f8d8a9f81c5fe2ff2febdb5f from 2020,
which also added -matomic in gcc.mk.
Things are also a bit messy in the different C libraries:
- uClibc is built with $(TARGET_ABI) and $(TARGET_DEBUGGING)
- glibc is built with $(TARGET_OPTIMIZATION) and a bunch of additional
flags
- musl is built with the full $(TARGET_CFLAGS)
Seems a bit meh to me.
So I think ideally we would to distinguish in a clear manner:
- CFLAGS that are passed through the wrapper, and which therefore need
to be manually passed when building gcc and C libraries
- CFLAGS that are passed through the environment
I think at least for now what could be done is to use
$(ARCH_TOOLCHAIN_WRAPPER_OPTS) in gcc.mk.
But I'm surprised they are not needed also in the C library build. Why
are you not seeing the same problem with the C library build, it should
also need the same page size flags, doesn't it?
Thomas
--
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Buildroot] [PATCH] arch: Set max/common-page-size for libgcc & libstdc++
2024-01-04 21:19 ` Thomas Petazzoni via buildroot
@ 2024-01-04 21:34 ` Yann E. MORIN
2024-01-04 21:38 ` Thomas Petazzoni via buildroot
0 siblings, 1 reply; 6+ messages in thread
From: Yann E. MORIN @ 2024-01-04 21:34 UTC (permalink / raw)
To: Thomas Petazzoni
Cc: Alexey Brodkin, Pavel Kozlov, Vladimir Isaev,
Alexey Brodkin via buildroot
Thomas, Alexey, All,
On 2024-01-04 22:19 +0100, Thomas Petazzoni spake thusly:
> On Wed, 3 Jan 2024 02:23:11 -0800
> Alexey Brodkin via buildroot <buildroot@buildroot.org> wrote:
> > I would agree that it gets more and more ugly, but so far I cannot see
> > any more elegant solution. So if there're suggestions how to improve,
> > let's discuss.
[--SNIP--]
> But I'm surprised they are not needed also in the C library build. Why
> are you not seeing the same problem with the C library build, it should
> also need the same page size flags, doesn't it?
It is my understanding that the toolchain wrapper is installed as a post
initial gcc hook as well:
package/gcc/gcc-initial/gcc-initial.mk:
59 HOST_GCC_INITIAL_POST_BUILD_HOOKS += TOOLCHAIN_WRAPPER_BUILD
60 HOST_GCC_INITIAL_POST_INSTALL_HOOKS += TOOLCHAIN_WRAPPER_INSTALL
61 HOST_GCC_INITIAL_POST_INSTALL_HOOKS += HOST_GCC_INSTALL_WRAPPER_AND_SIMPLE_SYMLINKS
So the C libraries are built using our wrapper.
Regards,
Yann E. MORIN.
--
.-----------------.--------------------.------------------.--------------------.
| Yann E. MORIN | Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: |
| +33 662 376 056 | Software Designer | \ / CAMPAIGN | ___ |
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Buildroot] [PATCH] arch: Set max/common-page-size for libgcc & libstdc++
2024-01-04 21:34 ` Yann E. MORIN
@ 2024-01-04 21:38 ` Thomas Petazzoni via buildroot
2024-01-04 22:22 ` Alexey Brodkin via buildroot
0 siblings, 1 reply; 6+ messages in thread
From: Thomas Petazzoni via buildroot @ 2024-01-04 21:38 UTC (permalink / raw)
To: Yann E. MORIN
Cc: Alexey Brodkin, Pavel Kozlov, Vladimir Isaev,
Alexey Brodkin via buildroot
On Thu, 4 Jan 2024 22:34:34 +0100
"Yann E. MORIN" <yann.morin.1998@free.fr> wrote:
> > But I'm surprised they are not needed also in the C library build. Why
> > are you not seeing the same problem with the C library build, it should
> > also need the same page size flags, doesn't it?
>
> It is my understanding that the toolchain wrapper is installed as a post
> initial gcc hook as well:
>
> package/gcc/gcc-initial/gcc-initial.mk:
> 59 HOST_GCC_INITIAL_POST_BUILD_HOOKS += TOOLCHAIN_WRAPPER_BUILD
> 60 HOST_GCC_INITIAL_POST_INSTALL_HOOKS += TOOLCHAIN_WRAPPER_INSTALL
> 61 HOST_GCC_INITIAL_POST_INSTALL_HOOKS += HOST_GCC_INSTALL_WRAPPER_AND_SIMPLE_SYMLINKS
>
> So the C libraries are built using our wrapper.
Hum, indeed. But then, why doesn't that apply to libgcc and libstdc++
as well? It is because libgcc/libstdc++ are built with the second stage
gcc, before it is installed and wrapped by our wrapper? I guess so
because the first stage gcc isn't capable of building shared libraries,
or something like that.
So, indeed, my proposal to Alexey is to use ARCH_TOOLCHAIN_WRAPPER_OPTS
in gcc.mk. This will allow to get rid of the special -matomic addition.
Thomas
--
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Buildroot] [PATCH] arch: Set max/common-page-size for libgcc & libstdc++
2024-01-04 21:38 ` Thomas Petazzoni via buildroot
@ 2024-01-04 22:22 ` Alexey Brodkin via buildroot
2024-01-04 22:42 ` Thomas Petazzoni via buildroot
0 siblings, 1 reply; 6+ messages in thread
From: Alexey Brodkin via buildroot @ 2024-01-04 22:22 UTC (permalink / raw)
To: Thomas Petazzoni, Yann E. MORIN
Cc: Pavel Kozlov, Vladimir Isaev, Alexey Brodkin via buildroot
Hi Thomas,
> On Thu, 4 Jan 2024 22:34:34 +0100
> "Yann E. MORIN" <yann.morin.1998@free.fr> wrote:
>
> > > But I'm surprised they are not needed also in the C library build. Why
> > > are you not seeing the same problem with the C library build, it should
> > > also need the same page size flags, doesn't it?
> >
> > It is my understanding that the toolchain wrapper is installed as a post
> > initial gcc hook as well:
> >
> > package/gcc/gcc-initial/gcc-initial.mk:
> > 59 HOST_GCC_INITIAL_POST_BUILD_HOOKS += TOOLCHAIN_WRAPPER_BUILD
> > 60 HOST_GCC_INITIAL_POST_INSTALL_HOOKS += TOOLCHAIN_WRAPPER_INSTALL
> > 61 HOST_GCC_INITIAL_POST_INSTALL_HOOKS += HOST_GCC_INSTALL_WRAPPER_AND_SIMPLE_SYMLINKS
> >
> > So the C libraries are built using our wrapper.
Right.
> Hum, indeed. But then, why doesn't that apply to libgcc and libstdc++
> as well? It is because libgcc/libstdc++ are built with the second stage
> gcc, before it is installed and wrapped by our wrapper? I guess so
> because the first stage gcc isn't capable of building shared libraries,
> or something like that.
libgcc_s.so.1 gets built with:
-------------------->8---------------------
.../output/build/host-gcc-final-arc-2023.09-release/build/./gcc/xgcc ... -o libgcc_s.so.1
-------------------->8---------------------
while libstdc++.so gets built with:
-------------------->8---------------------
libtool: link: .../buildroot/output/build/host-gcc-final-arc-2023.09-release/build/./gcc/xgcc ... -o .libs/libstdc++.so.6.0.32
-------------------->8---------------------
And that's the reason Buildroot toolchain wrapper doesn't affect them both.
Also from the snippets above you may see why they need separate env variables:
CFLAGS for libgcc and LDFLAGS for libstdc++.
BTW, that's the same problem I solved with adding "-matomic" flag on libgcc compilation via
https://git.buildroot.net/buildroot/commit/?id=d2ae7eb2a24c9033f8d8a9f81c5fe2ff2febdb5f
> So, indeed, my proposal to Alexey is to use ARCH_TOOLCHAIN_WRAPPER_OPTS
> in gcc.mk. This will allow to get rid of the special -matomic addition.
Do you mean something like that in gcc.mk?
----------------------->8---------------------
GCC_COMMON_TARGET_CFLAGS = $(TARGET_CFLAGS) $(ARCH_TOOLCHAIN_WRAPPER_OPTS)
GCC_COMMON_TARGET_CXXFLAGS = $(TARGET_CXXFLAGS) $(ARCH_TOOLCHAIN_WRAPPER_OPTS)
GCC_COMMON_TARGET_LDFLAGS = $(TARGET_LDFLAGS) $(ARCH_TOOLCHAIN_WRAPPER_OPTS)
----------------------->8---------------------
-Alexey
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Buildroot] [PATCH] arch: Set max/common-page-size for libgcc & libstdc++
2024-01-04 22:22 ` Alexey Brodkin via buildroot
@ 2024-01-04 22:42 ` Thomas Petazzoni via buildroot
0 siblings, 0 replies; 6+ messages in thread
From: Thomas Petazzoni via buildroot @ 2024-01-04 22:42 UTC (permalink / raw)
To: Alexey Brodkin
Cc: Pavel Kozlov, Yann E. MORIN, Vladimir Isaev,
Alexey Brodkin via buildroot
On Thu, 4 Jan 2024 22:22:45 +0000
Alexey Brodkin <Alexey.Brodkin@synopsys.com> wrote:
> Do you mean something like that in gcc.mk?
> ----------------------->8---------------------
> GCC_COMMON_TARGET_CFLAGS = $(TARGET_CFLAGS) $(ARCH_TOOLCHAIN_WRAPPER_OPTS)
> GCC_COMMON_TARGET_CXXFLAGS = $(TARGET_CXXFLAGS) $(ARCH_TOOLCHAIN_WRAPPER_OPTS)
> GCC_COMMON_TARGET_LDFLAGS = $(TARGET_LDFLAGS) $(ARCH_TOOLCHAIN_WRAPPER_OPTS)
> ----------------------->8---------------------
Yes, exactly, and removing:
# Make sure libgcc & libstdc++ always get built with -matomic on ARC700
ifeq ($(GCC_TARGET_CPU):$(BR2_ARC_ATOMIC_EXT),arc700:y)
GCC_COMMON_TARGET_CFLAGS += -matomic
GCC_COMMON_TARGET_CXXFLAGS += -matomic
endif
because this will now be taken care of by $(ARCH_TOOLCHAIN_WRAPPER_OPTS)
Thomas
--
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Embedded Linux and Kernel engineering and training
https://bootlin.com
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2024-01-03 10:23 [Buildroot] [PATCH] arch: Set max/common-page-size for libgcc & libstdc++ Alexey Brodkin via buildroot
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2024-01-04 21:34 ` Yann E. MORIN
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