[lfs-support] Rather a lot of glibc check errors

[Hazel Russman]

Building LFS 8.1 on my Samsung laptop, I was surprised to see a large number of math errors in the chapter 6 glibc check:

The failed tests were: float-cabs, float-fma, float32-cabs,
float32-fma, float64x-acosh, float64x-atan, float64x-atan2,
float64x-cacos, float64x-casin, float64x-casinh, float64x-catanh,
float64x-clog, float64x-clog10, float64x-finite-acosh, float64x-finite-atan, float64x-finite-atan2, float64x-finite-cacos,
float64x-finite-casin, float64x-finite-casinh, float64x-finite-catanh,
float64x-finite-clog, float64x-finite-clog10, float64x-finite-log10,
float64x-log10, ifloat64x-acosh, ifloat64x-atan2, ifloat64x-cacos, ifloat64x-casin, ifloat64x-casinh, ifloat64x-catanh, ifloat64x-clog, ifloat64x-clog10, ildouble-acosh, ildouble-atan2, ildouble-cacos, ildouble-casin, ildouble-casinh, ildouble-catanh, ildouble-clog, ildouble-clog10, ildouble-log10, ldouble-acosh, ldouble-atan, ldouble-atan2, ldouble-cacos, ldouble-casin, ldouble-casinh, ldouble-catanh, ldouble-clog, ldouble-clog10, ldouble-finite-acosh, ldouble-finite-atan, ldouble-finite-atan2, ldouble-finite-cacos, ldouble-finite-casin, ldouble-finite-casinh, ldouble-finite-catanh, ldouble-finite-clog,
ldouble-finite-clog10, ldouble-finite-log10, ldouble-log10.

I've never had so many failures before. ISTR that earlier editions of LFS warned about failures in maths tests on non-intel non-amd processors (the Samsung has a Via nano) but 8.1 doesn't mention this.

Do I need to rebuild and, if so, can anyone suggest what parameters I might need to use to avoid a repetition?
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[Ken Moffat]

Post by Hazel Russman
The failed tests were: float-cabs, float-fma, float32-cabs,
float32-fma, float64x-acosh, float64x-atan, float64x-atan2,
float64x-cacos, float64x-casin, float64x-casinh, float64x-catanh,
float64x-clog, float64x-clog10, float64x-finite-acosh, float64x-finite-atan, float64x-finite-atan2, float64x-finite-cacos,
float64x-finite-casin, float64x-finite-casinh, float64x-finite-catanh,
float64x-finite-clog, float64x-finite-clog10, float64x-finite-log10,
float64x-log10, ifloat64x-acosh, ifloat64x-atan2, ifloat64x-cacos, ifloat64x-casin, ifloat64x-casinh, ifloat64x-catanh, ifloat64x-clog, ifloat64x-clog10, ildouble-acosh, ildouble-atan2, ildouble-cacos, ildouble-casin, ildouble-casinh, ildouble-catanh, ildouble-clog, ildouble-clog10, ildouble-log10, ldouble-acosh, ldouble-atan, ldouble-atan2, ldouble-cacos, ldouble-casin, ldouble-casinh, ldouble-catanh, ldouble-clog, ldouble-clog10, ldouble-finite-acosh, ldouble-finite-atan, ldouble-finite-atan2, ldouble-finite-cacos, ldouble-finite-casin, ldouble-finite-casinh, ldouble-finite-catanh, ldouble-finite-clog,
ldouble-finite-clog10, ldouble-finite-log10, ldouble-log10.

Hi Hazel,

googling for a couple of random tests in that list found failures in
the release notes for glibc-2.26, which I think you are using, and
glibc-2.27. But they were all on other architectures.

Post by Hazel Russman
I've never had so many failures before. ISTR that earlier editions of LFS warned about failures in maths tests on non-intel non-amd processors (the Samsung has a Via nano) but 8.1 doesn't mention this.

I suspect we removed that text because nobody who follows the dev
list has non-intel non-AMD x86 CPUs these days.

Post by Hazel Russman
Do I need to rebuild and, if so, can anyone suggest what parameters I might need to use to avoid a repetition?

The proof of the pudding is in the eating! Probably very few
people, if any, are using this CPU to build and test packages such
as glibc. Usually, a test failure does not cause any noticeable
problems at runtime.

I would suggest you continue.

ĸen

Post by Hazel Russman
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[Hazel Russman]

On Tue, 12 Jun 2018 20:11:10 +0100

Post by Ken Moffat

Post by Hazel Russman
Do I need to rebuild and, if so, can anyone suggest what parameters I might need to use to avoid a repetition?

The proof of the pudding is in the eating! Probably very few
people, if any, are using this CPU to build and test packages such
as glibc. Usually, a test failure does not cause any noticeable
problems at runtime.
I would suggest you continue.
ĸen

That's my preferred solution too, for obvious reasons! But your advice puzzles me all the same. If the test results really don't matter, even when you get a lot of errors, why does the book emphasise the need to carry out these tests for glibc, binutils, gcc and the three gcc libraries?
<quote>
Important:
In this section, the test suite for Glibc is considered critical. Do not skip it under any circumstance.
</quote>
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[Bruce Dubbs]

Post by Hazel Russman
On Tue, 12 Jun 2018 20:11:10 +0100

Post by Ken Moffat

Post by Hazel Russman
Do I need to rebuild and, if so, can anyone suggest what parameters I might need to use to avoid a repetition?

The proof of the pudding is in the eating! Probably very few
people, if any, are using this CPU to build and test packages such
as glibc. Usually, a test failure does not cause any noticeable
problems at runtime.
I would suggest you continue.
ĸen

That's my preferred solution too, for obvious reasons! But your advice puzzles me all the same. If the test results really don't matter, even when you get a lot of errors, why does the book emphasise the need to carry out these tests for glibc, binutils, gcc and the three gcc libraries?
<quote>
In this section, the test suite for Glibc is considered critical. Do not skip it under any circumstance.
</quote>

Because the book targets x86_64 (and to a certain extent x86). On those
systems the number of failures is very few. The tool chain (binutils,
glibc, and gcc) is critical to the rest of the book and undocumented
failures there would cascade throughout the rest of the book.

-- Bruce
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http://en.

[Ken Moffat]

Post by Bruce Dubbs

Post by Hazel Russman
On Tue, 12 Jun 2018 20:11:10 +0100

Post by Ken Moffat
I would suggest you continue.
ĸen

That's my preferred solution too, for obvious reasons! But your advice puzzles me all the same. If the test results really don't matter, even when you get a lot of errors, why does the book emphasise the need to carry out these tests for glibc, binutils, gcc and the three gcc libraries?
<quote>
In this section, the test suite for Glibc is considered critical. Do not skip it under any circumstance.
</quote>

Because the book targets x86_64 (and to a certain extent x86). On those
systems the number of failures is very few. The tool chain (binutils,
glibc, and gcc) is critical to the rest of the book and undocumented
failures there would cascade throughout the rest of the book.

Technically, Hazel's machine (Via Nano) *is* x86 (or x86_64), at least
according to wikipedia. It just happens to be a slightly unknown
quantity to the rest of us.

A year ago Hazel had the math failures and two others here -
http://lists.linuxfromscratch.org/pipermail/lfs-support/2017-January/050742.html

Maybe we should reinstate the words in some form.

ĸen
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[Bruce Dubbs]

Post by Ken Moffat

Post by Bruce Dubbs

Post by Hazel Russman
On Tue, 12 Jun 2018 20:11:10 +0100

Post by Ken Moffat
I would suggest you continue.
ĸen

That's my preferred solution too, for obvious reasons! But your advice puzzles me all the same. If the test results really don't matter, even when you get a lot of errors, why does the book emphasise the need to carry out these tests for glibc, binutils, gcc and the three gcc libraries?
<quote>
In this section, the test suite for Glibc is considered critical. Do not skip it under any circumstance.
</quote>

Because the book targets x86_64 (and to a certain extent x86). On those
systems the number of failures is very few. The tool chain (binutils,
glibc, and gcc) is critical to the rest of the book and undocumented
failures there would cascade throughout the rest of the book.

Technically, Hazel's machine (Via Nano) *is* x86 (or x86_64), at least
according to wikipedia. It just happens to be a slightly unknown
quantity to the rest of us.
A year ago Hazel had the math failures and two others here -
http://lists.linuxfromscratch.org/pipermail/lfs-support/2017-January/050742.html
Maybe we should reinstate the words in some form.

What words?

-- Bruce
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http://en.wikipedia

[Ken Moffat]

Post by Bruce Dubbs

Post by Ken Moffat
Maybe we should reinstate the words in some form.

What words?

I think Hazel quoted something from an earlier version of the book,
but I'm not sure where it was placed (in a quick look at chapter 6
glibc in 7.10 and 8.0 I didn't spot anything about non-intel
non-AMD.

ĸen
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[Hazel Russman]

On Thu, 14 Jun 2018 19:26:01 +0100

Post by Ken Moffat

Post by Bruce Dubbs

Post by Ken Moffat
Maybe we should reinstate the words in some form.

What words?

I think Hazel quoted something from an earlier version of the book,
but I'm not sure where it was placed (in a quick look at chapter 6
glibc in 7.10 and 8.0 I didn't spot anything about non-intel
non-AMD.
ĸen

Here's a quote brom LFS 7.7, chap 6.9:
The math tests sometimes fail when running on systems where the CPU is not a relatively new genuine Intel or authentic AMD processor.
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[lei niu]

Hazel, trust me. Even you use most recently produced Intel or AMD CPU, several tests may still fail. niuneilneo 邮箱***@gmail.com 筟名由 眑易邮箱倧垈 定制 On 06/15/2018 14:14, Hazel Russman wrote: On Thu, 14 Jun 2018 19:26:01 +0100 Ken Moffat <***@ntlworld.com> wrote: > On Thu, Jun 14, 2018 at 10:33:56AM -0500, Bruce Dubbs wrote: > > On 06/14/2018 05:18 AM, Ken Moffat wrote:   > > > > > > Maybe we should reinstate the words in some form.   > > > > What words? > >   > I think Hazel quoted something from an earlier version of the book, > but I'm not sure where it was placed (in a quick look at chapter 6 > glibc in 7.10 and 8.0 I didn't spot anything about non-intel > non-AMD. > > Äžen Here's a quote brom LFS 7.7, chap 6.9: The math tests sometimes fail when running on systems where the CPU is not a relatively new genuine Intel or authentic AMD processor. -- Hazel -- http://lists.linuxfromscratch.org/listinfo/lfs-support FAQ: http://www.linuxfromscratch.org/blfs/faq.html Unsubscribe: See the above information page Do not top post on this list. A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail? http://en.wikipedia.org/wiki/Posting_style

[Bruce Dubbs]

Post by Hazel Russman
On Thu, 14 Jun 2018 19:26:01 +0100

Post by Ken Moffat

Post by Bruce Dubbs

Post by Ken Moffat
Maybe we should reinstate the words in some form.

What words?

I think Hazel quoted something from an earlier version of the book,
but I'm not sure where it was placed (in a quick look at chapter 6
glibc in 7.10 and 8.0 I didn't spot anything about non-intel
non-AMD.
ĸen

The math tests sometimes fail when running on systems where the CPU is not a relatively new genuine Intel or authentic AMD processor.

It turns out that that is still in the book's source in a comment. I
uncommented it in revision 11421.

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[Hazel Russman]

On Thu, 14 Jun 2018 11:18:10 +0100

Post by Ken Moffat

Post by Bruce Dubbs
Because the book targets x86_64 (and to a certain extent x86). On those
systems the number of failures is very few. The tool chain (binutils,
glibc, and gcc) is critical to the rest of the book and undocumented
failures there would cascade throughout the rest of the book.

Technically, Hazel's machine (Via Nano) *is* x86 (or x86_64), at least
according to wikipedia. It just happens to be a slightly unknown
quantity to the rest of us.
A year ago Hazel had the math failures and two others here -
http://lists.linuxfromscratch.org/pipermail/lfs-support/2017-January/050742.html
Maybe we should reinstate the words in some form.
ĸen
--

I only had half a dozen math errors last time around and that's tolerable. This glibc gives a lot more, over 60! As I hadn't yet installed it, I decided to scrap it and rebuild with -march=nano-2000. I've just viewed the results and they are no better.

I'm going to proceed anyway and see if I run into Bruce's "cascade of errors". If so, it may mean that LFS with an up-to-date glibc can no longer be built on this processor. I shall have to stick to binary distros from now on.

Fortunately LFS still builds just fine on my main desktop, which is Intel throughout.
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[Paul Rogers]

FWIW, I've built and run LFS-7.7 on a 1.0 GHz VIA C7 "Esther", a Pentium-3 "work alike". It's a "scalar" core with branch prediction, but none of the super-scalar out-of-order execution that has become so much of a problem. I rather like the idea of working on a processor that runs at less than 10W, and the mini-ITX infrastructure makes a nice small system. It was a bit of a "heavy lift" for the processor, so I typically go back to 7.2.
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[Hazel Russman]

On Thu, 14 Jun 2018 14:13:12 -0700

Post by Paul Rogers
FWIW, I've built and run LFS-7.7 on a 1.0 GHz VIA C7 "Esther", a Pentium-3 "work alike". It's a "scalar" core with branch prediction, but none of the super-scalar out-of-order execution that has become so much of a problem. I rather like the idea of working on a processor that runs at less than 10W, and the mini-ITX infrastructure makes a nice small system. It was a bit of a "heavy lift" for the processor, so I typically go back to 7.2.

Well, I continued and have just signed off a completely normal gcc test: only 1 unexpected error (in gcc itself, which I think I had the last time too), plus the 6 expected ones in libstdc++. I seem to have a sane toolchain.

Interestingly gmp and mpfr both identify my machine as "nano-pc-linux-gnu" rather than x86_64-pc-linux-gnu, so Bruce is sort-of right when he calls it a different architecture. They both set themselves up to run with -march=nano -mtune=nano. What glibc thought it was building on, I have no idea, as I couldn't find a config.guess script in the package.

The real test will be whether I can build a bootable kernel.
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[Ken Moffat]

Post by Hazel Russman
On Thu, 14 Jun 2018 14:13:12 -0700
Well, I continued and have just signed off a completely normal gcc test: only 1 unexpected error (in gcc itself, which I think I had the last time too), plus the 6 expected ones in libstdc++. I seem to have a sane toolchain.

Good ;-)

Post by Hazel Russman
Interestingly gmp and mpfr both identify my machine as "nano-pc-linux-gnu" rather than x86_64-pc-linux-gnu, so Bruce is sort-of right when he calls it a different architecture. They both set themselves up to run with -march=nano -mtune=nano. What glibc thought it was building on, I have no idea, as I couldn't find a config.guess script in the package.

I'm surprised by nano-pc-linux-gnu.

But to find what -march=native will use, here are a couple of
answers from

https://stackoverflow.com/questions/5470257/how-to-see-which-flags-march-native-will-activate

(there were other suggestions too, of course) -

The second answer suggested:

gcc -march=native -E -v - </dev/null 2>&1 | grep cc1

and also, to see the defines:

echo | gcc -dM -E - -march=native

The third answer suggested:

echo | gcc -### -E - -march=native

Post by Hazel Russman
The real test will be whether I can build a bootable kernel.

Indeed, but here's hoping.

ĸen
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[Xi Ruoyao]

Post by Ken Moffat

Post by Hazel Russman
Interestingly gmp and mpfr both identify my machine as "nano-pc-linux-gnu" rather than x86_64-pc-linux-gnu, so Bruce
is sort-of right when he calls it a different architecture. They both set themselves up to run with -march=nano
-mtune=nano. What glibc thought it was building on, I have no idea, as I couldn't find a config.guess script in the
package.

I'm surprised by nano-pc-linux-gnu.

No surprise here. GMP's config.guess is special. It outputs "ivybridge-pc-linux-gnu",
"skylake-pc-linux-gnu", "k8-pc-linux-gnu" etc.

"uname -m" would still output "x86_64".
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[Hazel Russman]

On Sat, 16 Jun 2018 23:03:05 +0800

Post by Xi Ruoyao

Post by Ken Moffat

Post by Hazel Russman
Interestingly gmp and mpfr both identify my machine as "nano-pc-linux-gnu" rather than x86_64-pc-linux-gnu, so Bruce
is sort-of right when he calls it a different architecture. They both set themselves up to run with -march=nano
-mtune=nano. What glibc thought it was building on, I have no idea, as I couldn't find a config.guess script in the
package.

I'm surprised by nano-pc-linux-gnu.

No surprise here. GMP's config.guess is special. It outputs "ivybridge-pc-linux-gnu",
"skylake-pc-linux-gnu", "k8-pc-linux-gnu" etc.
"uname -m" would still output "x86_64".
--

--
Update: in spite of the sheaf of math errors in glibc, I did finally arrive at a bootable system. I ran "make check" on every package (something I don't usually do these days) and, with one exception, saw nothing very unusual. Just the odd test failing that should have passed and the odd test passing that (according to the book) should have failed.

The exception was when I was checking gettext and it kept crashing. The kernel log showed segfaults in glibc. I was low on power at the time; when I recharged fully and ran the tests again, everything went smoothly. So it seems there may be some instability in my glibc after all but it only manifests at low power. I can live with that.
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[Hazel Russman]

On Sat, 16 Jun 2018 15:16:06 +0100

Post by Ken Moffat

Post by Hazel Russman
On Thu, 14 Jun 2018 14:13:12 -0700
Well, I continued and have just signed off a completely normal gcc test: only 1 unexpected error (in gcc itself, which I think I had the last time too), plus the 6 expected ones in libstdc++. I seem to have a sane toolchain.

Good ;-)

Post by Hazel Russman
Interestingly gmp and mpfr both identify my machine as "nano-pc-linux-gnu" rather than x86_64-pc-linux-gnu, so Bruce is sort-of right when he calls it a different architecture. They both set themselves up to run with -march=nano -mtune=nano. What glibc thought it was building on, I have no idea, as I couldn't find a config.guess script in the package.

I'm surprised by nano-pc-linux-gnu.
But to find what -march=native will use, here are a couple of
answers from
https://stackoverflow.com/questions/5470257/how-to-see-which-flags-march-native-will-activate
(there were other suggestions too, of course) -
gcc -march=native -E -v - </dev/null 2>&1 | grep cc1
echo | gcc -dM -E - -march=native
echo | gcc -### -E - -march=native
ĸen
--

For both 1 & 3, I get -march=nano -mtune=k8. The defines have x86_64, amd64 and k8 set but nothing for nano. I know that amd64 is used by Debian for all x86_64 processors, but k8 puzzles me. Isn't that also an amd processor?

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Hazel
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