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poco: disable fpenvironment for MIPS without FPU

PATCH Superseded yegorslists at googlemail.com 3 participants 9 messages Oct 9, 2018 – Oct 10, 2018

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#0 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

From: Yegor Yefremov <[email protected]>

glibc fixed a bug, that defined FPU capabilities not available for MIPS without FPU. So add --no-fpenvironment to the configuration options for this case.

Signed-off-by Yegor Yefremov <[email protected]>

---
Changes v1 -> v2:
- put all conditions in one ifeq statement (Thomas Petazzoni)

 package/poco/poco.mk | 5 +++++
 1 file changed, 5 insertions(+)
package/poco/poco.mk +5 -0
index 018344d5c7..af41d36ff7 100644
@@ -42,6 +42,11 @@ ifeq ($(BR2_sh4a)$(BR2_nios2),y)
 POCO_CONF_OPTS += --no-fpenvironment
 endif
 
+# MIPS without FPU
+ifeq ($(BR2_mips)$(BR2_mipsel)$(BR2_mips64)$(BR2_mips64el):$(BR2_MIPS_SOFT_FLOAT),y:y)
+POCO_CONF_OPTS += --no-fpenvironment
+endif
+
 ifeq ($(BR2_STATIC_LIBS),y)
 POCO_MAKE_TARGET = static_release
 else ifeq ($(BR2_SHARED_LIBS),y)
Signature · 1 line
2.17.0
#1 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

Quoted 5 lines · yegorslists at googlemail.com

From: Yegor Yefremov <[email protected]>

glibc fixed a bug, that defined FPU capabilities not available for MIPS without FPU. So add --no-fpenvironment to the configuration options for this case.

The commit message is still very vague. I think I understand it though,
something like:

On MIPS soft-float, glibc defines some FPU capabilities in fpenv that don't actually exist. This is a bug that has been fixed in glibc but not yet released. Therefore, pass --no-fpenvironment to disable floating-point operations entirely.

It would also be nice to point to the glibc bug.

Quoted 14 lines
Signed-off-by Yegor Yefremov <[email protected]>

---
Changes v1 -> v2:
- put all conditions in one ifeq statement (Thomas Petazzoni)

 package/poco/poco.mk | 5 +++++
 1 file changed, 5 insertions(+)
package/poco/poco.mk +0 -0
index 018344d5c7..af41d36ff7 100644

package/poco/poco.mk ifeq ($(BR2_sh4a)$(BR2_nios2),y) · line 46

Quoted 5 lines
package/poco/poco.mk +2 -0
@@ -42,6 +42,11 @@ ifeq ($(BR2_sh4a)$(BR2_nios2),y)
 POCO_CONF_OPTS += --no-fpenvironment
 endif
 
+# MIPS without FPU
+ifeq ($(BR2_mips)$(BR2_mipsel)$(BR2_mips64)$(BR2_mips64el):$(BR2_MIPS_SOFT_FLOAT),y:y)

BR2_MIPS_SOFT_FLOAT is only defined on MIPS, so it is sufficient to do

ifeq ($(BR2_MIPS_SOFT_FLOAT),y)

However, since this is about a glibc bug, shouldn't it check for a glibc
toolchain as well?

Regards,
Arnout

Quoted 7 lines
package/poco/poco.mk +3 -0
+POCO_CONF_OPTS += --no-fpenvironment
+endif
+
 ifeq ($(BR2_STATIC_LIBS),y)
 POCO_MAKE_TARGET = static_release
 else ifeq ($(BR2_SHARED_LIBS),y)
Signature · 6 lines
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF
#2 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

Hello,

Quoted 2 lines · Arnout Vandecappelle

The commit message is still very vague. I think I understand it though,
something like:

Yes, I agree the commit log was still too vague.

Quoted 9 lines

package/poco/poco.mk ifeq ($(BR2_sh4a)$(BR2_nios2),y) · line 46

Quoted 2 lines
package/poco/poco.mk +2 -0
+# MIPS without FPU
+ifeq ($(BR2_mips)$(BR2_mipsel)$(BR2_mips64)$(BR2_mips64el):$(BR2_MIPS_SOFT_FLOAT),y:y)

BR2_MIPS_SOFT_FLOAT is only defined on MIPS, so it is sufficient to do

ifeq ($(BR2_MIPS_SOFT_FLOAT),y)

However, since this is about a glibc bug, shouldn't it check for a glibc
toolchain as well?

Isn't the glibc bug that it allowed to use fpenv in situations where it shouldn't have allowed it ? If that's the case, perhaps the other libcs didn't had this bug, and fpenv really shouldn't be used with MIPS soft-float, regardless of the C library in use ?

Best regards,

Thomas

Signature · 3 lines
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
author
#3 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

Quoted 17 lines · Thomas Petazzoni

Hello,

Quoted 2 lines · Arnout Vandecappelle

The commit message is still very vague. I think I understand it though,
something like:

Yes, I agree the commit log was still too vague.

Quoted 7 lines

package/poco/poco.mk ifeq ($(BR2_sh4a)$(BR2_nios2),y) · line 46

Quoted 2 lines
package/poco/poco.mk +2 -0
+# MIPS without FPU
+ifeq ($(BR2_mips)$(BR2_mipsel)$(BR2_mips64)$(BR2_mips64el):$(BR2_MIPS_SOFT_FLOAT),y:y)

BR2_MIPS_SOFT_FLOAT is only defined on MIPS, so it is sufficient to do

ifeq ($(BR2_MIPS_SOFT_FLOAT),y)

Quoted 7 lines
Quoted 2 lines

However, since this is about a glibc bug, shouldn't it check for a glibc
toolchain as well?

Isn't the glibc bug that it allowed to use fpenv in situations where it shouldn't have allowed it ? If that's the case, perhaps the other libcs didn't had this bug, and fpenv really shouldn't be used with MIPS soft-float, regardless of the C library in use ?

I've made a compile test with musl and it fails too. So I'll just disable fpenv if BR2_MIPS_SOFT_FLOAT is selected. So ne need to mention glibc.

Strange, that it didn't show up in the build tests ...

Yegor

author
#4 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

Quoted 28 lines · Yegor Yefremov
Quoted 17 lines · Thomas Petazzoni

Hello,

Quoted 2 lines · Arnout Vandecappelle

The commit message is still very vague. I think I understand it though,
something like:

Yes, I agree the commit log was still too vague.

Quoted 7 lines

package/poco/poco.mk ifeq ($(BR2_sh4a)$(BR2_nios2),y) · line 46

Quoted 2 lines
package/poco/poco.mk +2 -0
+# MIPS without FPU
+ifeq ($(BR2_mips)$(BR2_mipsel)$(BR2_mips64)$(BR2_mips64el):$(BR2_MIPS_SOFT_FLOAT),y:y)

BR2_MIPS_SOFT_FLOAT is only defined on MIPS, so it is sufficient to do

ifeq ($(BR2_MIPS_SOFT_FLOAT),y)

Quoted 7 lines
Quoted 2 lines

However, since this is about a glibc bug, shouldn't it check for a glibc
toolchain as well?

Isn't the glibc bug that it allowed to use fpenv in situations where it shouldn't have allowed it ? If that's the case, perhaps the other libcs didn't had this bug, and fpenv really shouldn't be used with MIPS soft-float, regardless of the C library in use ?

Quoted 5 lines

I've made a compile test with musl and it fails too. So I'll just disable fpenv if BR2_MIPS_SOFT_FLOAT is selected. So ne need to mention glibc.

Strange, that it didn't show up in the build tests ...

For now we disable fpenv for two archs:

# architectures missing some FE_* in their fenv.h
ifeq ($(BR2_sh4a)$(BR2_nios2),y)
POCO_CONF_OPTS += --no-fpenvironment
endif

Should I just add $(BR2_MIPS_SOFT_FLOAT) to this statement even without changing the comment?

Yegor

#5 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

In reply to Yegor Yefremov

Hello,

Quoted 10 lines · Yegor Yefremov
Quoted 4 lines

Isn't the glibc bug that it allowed to use fpenv in situations where it shouldn't have allowed it ? If that's the case, perhaps the other libcs didn't had this bug, and fpenv really shouldn't be used with MIPS soft-float, regardless of the C library in use ?

I've made a compile test with musl and it fails too. So I'll just disable fpenv if BR2_MIPS_SOFT_FLOAT is selected. So ne need to mention glibc.

Strange, that it didn't show up in the build tests ...

We don't test mips/musl in the autobuilders. However, we do test mips/uclibc, but maybe not in soft-float mode.

Thomas

Signature · 3 lines
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
author
#6 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

Quoted 10 lines · Thomas Petazzoni

Hello,

Quoted 5 lines · Yegor Yefremov
Quoted 4 lines

Isn't the glibc bug that it allowed to use fpenv in situations where it shouldn't have allowed it ? If that's the case, perhaps the other libcs didn't had this bug, and fpenv really shouldn't be used with MIPS soft-float, regardless of the C library in use ?

Quoted 8 lines
Quoted 5 lines

I've made a compile test with musl and it fails too. So I'll just disable fpenv if BR2_MIPS_SOFT_FLOAT is selected. So ne need to mention glibc.

Strange, that it didn't show up in the build tests ...

We don't test mips/musl in the autobuilders. However, we do test mips/uclibc, but maybe not in soft-float mode.

uclibc has special handling: both fpenv and wstring will be disabled.

Yegor

#7 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

Quoted 16 lines · Yegor Yefremov
Quoted 14 lines · Thomas Petazzoni

Hello,

Quoted 9 lines · Yegor Yefremov
Quoted 4 lines

Isn't the glibc bug that it allowed to use fpenv in situations where it shouldn't have allowed it ? If that's the case, perhaps the other libcs didn't had this bug, and fpenv really shouldn't be used with MIPS soft-float, regardless of the C library in use ?

I've made a compile test with musl and it fails too. So I'll just disable fpenv if BR2_MIPS_SOFT_FLOAT is selected. So ne need to mention glibc.

Quoted 6 lines
Quoted 4 lines
Quoted 1 line

Strange, that it didn't show up in the build tests ...

We don't test mips/musl in the autobuilders. However, we do test mips/uclibc, but maybe not in soft-float mode.

uclibc has special handling: both fpenv and wstring will be disabled.

So, to be fully correct, poco should be build-tested and preferably
runtime-tested on all these softfloat architectures.

Wouldn't it be a lot simpler to just disable the whole fpenv stuff on soft
float unconditionally? Yes, this is not perfect, because there are a few cases where it actually *does* work. But if someone needs those cases, let them please write a proper configure script that detects them. Until then, disable the entire feature on soft float.

Regards,
Arnout

Signature · 6 lines
Arnout Vandecappelle                          arnout at mind be
Senior Embedded Software Architect            +32-16-286500
Essensium/Mind                                http://www.mind.be
G.Geenslaan 9, 3001 Leuven, Belgium           BE 872 984 063 RPR Leuven
LinkedIn profile: http://www.linkedin.com/in/arnoutvandecappelle
GPG fingerprint:  7493 020B C7E3 8618 8DEC 222C 82EB F404 F9AC 0DDF
author
#8 lore raw

PATCH v2 1/1 poco: disable fpenvironment for MIPS without FPU

Quoted 27 lines · Arnout Vandecappelle
Quoted 16 lines · Yegor Yefremov
Quoted 14 lines · Thomas Petazzoni

Hello,

Quoted 9 lines · Yegor Yefremov
Quoted 4 lines

Isn't the glibc bug that it allowed to use fpenv in situations where it shouldn't have allowed it ? If that's the case, perhaps the other libcs didn't had this bug, and fpenv really shouldn't be used with MIPS soft-float, regardless of the C library in use ?

I've made a compile test with musl and it fails too. So I'll just disable fpenv if BR2_MIPS_SOFT_FLOAT is selected. So ne need to mention glibc.

Quoted 6 lines
Quoted 4 lines
Quoted 1 line

Strange, that it didn't show up in the build tests ...

We don't test mips/musl in the autobuilders. However, we do test mips/uclibc, but maybe not in soft-float mode.

uclibc has special handling: both fpenv and wstring will be disabled.

Quoted 8 lines

So, to be fully correct, poco should be build-tested and preferably
runtime-tested on all these softfloat architectures.

Wouldn't it be a lot simpler to just disable the whole fpenv stuff on soft
float unconditionally? Yes, this is not perfect, because there are a few cases where it actually *does* work. But if someone needs those cases, let them please write a proper configure script that detects them. Until then, disable the entire feature on soft float.

Patch already sent. I've tried ARM with soft floating point and it also fails with enabled fpenvironment.

Yegor