Add support for FreeBSD on x86 #163

gchatelet · 2021-06-25T07:46:26Z

This is replacing #159 and fixes #158

gchatelet · 2021-06-25T07:52:00Z

To submit when we have continuous integration for FreeBSD via Vagrant.

Mizux · 2021-06-25T08:19:32Z

src/cpuinfo_x86.c

+    if (fd >= 0) {
+      StackLineReader reader;
+      StackLineReader_Initialize(&reader, fd);
+      for (;;) {


Out of curiosity, is there any difference with using while (true) { ?
EDIT: you're using for (;;) also just below so for consistency, we should at least use the same semantic in both cases.

No difference between for(;;) and while(true). We could use either one.

src/cpuinfo_x86.c

Mizux

two comments...

vishwin · 2021-06-25T18:39:12Z

test/cpuinfo_x86_test.cc

+#elif defined(CPU_FEATURES_OS_FREEBSD)
+  auto& fs = GetEmptyFilesystem();
+  fs.CreateFile("/var/run/dmesg.boot", R"(
+  ---<<BOOT>>---


Even though this will be moot when the branch goes EOL at the end of September, FreeBSD 11 does not have this line in dmesg.boot.

Ack. It was present in a dump of a FreeBSD 12.2-RELEASE r366954 GENERIC amd64

---<<BOOT>>--- Copyright (c) 1992-2020 The FreeBSD Project. Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994 The Regents of the University of California. All rights reserved. FreeBSD is a registered trademark of The FreeBSD Foundation. FreeBSD 12.2-RELEASE r366954 GENERIC amd64 FreeBSD clang version 10.0.1 (git@github.com:llvm/llvm-project.git llvmorg-10.0.1-0-gef32c611aa2) VT(vga): text 80x25 module vtnet already present! CPU: Intel(R) Core(TM) i7-10710U CPU @ 1.10GHz (1607.96-MHz K8-class CPU) Origin="GenuineIntel" Id=0xa0660 Family=0x6 Model=0xa6 Stepping=0 Features=0x1783fbff<FPU,VME,DE,PSE,TSC,MSR,PAE,MCE,CX8,APIC,SEP,MTRR,PGE,MCA,CMOV,PAT,PSE36,MMX,FXSR,SSE,SSE2,HTT> Features2=0x5eda2203<SSE3,PCLMULQDQ,SSSE3,CX16,PCID,SSE4.1,SSE4.2,MOVBE,POPCNT,AESNI,XSAVE,OSXSAVE,AVX,RDRAND> AMD Features=0x28100800<SYSCALL,NX,RDTSCP,LM> AMD Features2=0x121<LAHF,ABM,Prefetch> Structured Extended Features=0x842421<FSGSBASE,AVX2,INVPCID,NFPUSG,RDSEED,CLFLUSHOPT> Structured Extended Features3=0x30000400<MD_CLEAR,L1DFL,ARCH_CAP> TSC: P-state invariant real memory = 2147418112 (2047 MB) avail memory = 2044313600 (1949 MB)

FWIW we don't use this line but it's a representative input.

vishwin · 2021-06-25T21:40:42Z

Already failing on 14-CURRENT:

[  2% 5/110] /ccache/libexec/ccache/cc -DSTACK_LINE_READER_BUFFER_SIZE=1024 -D_GLIBCXX_USE_CXX11_ABI=1 -I/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/include -I/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/include/internal -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -Wall -Werror=incompatible-pointer-types -Werror=pointer-sign -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -fPIC -std=gnu99 -MD -MT cpu_features/CMakeFiles/cpu_features.dir/src/cpuinfo_x86.c.o -MF cpu_features/CMakeFiles/cpu_features.dir/src/cpuinfo_x86.c.o.d -o cpu_features/CMakeFiles/cpu_features.dir/src/cpuinfo_x86.c.o -c /wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c
FAILED: cpu_features/CMakeFiles/cpu_features.dir/src/cpuinfo_x86.c.o
/ccache/libexec/ccache/cc -DSTACK_LINE_READER_BUFFER_SIZE=1024 -D_GLIBCXX_USE_CXX11_ABI=1 -I/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/include -I/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/include/internal -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -Wall -Werror=incompatible-pointer-types -Werror=pointer-sign -O2 -pipe -fstack-protector-strong -fno-strict-aliasing -fPIC -std=gnu99 -MD -MT cpu_features/CMakeFiles/cpu_features.dir/src/cpuinfo_x86.c.o -MF cpu_features/CMakeFiles/cpu_features.dir/src/cpuinfo_x86.c.o.d -o cpu_features/CMakeFiles/cpu_features.dir/src/cpuinfo_x86.c.o -c /wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:111:2: error: "Unsupported OS"
#error "Unsupported OS"
 ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1335:20: warning: implicit declaration of function 'CpuFeatures_OpenFile' is invalid in C99 [-Wimplicit-function-declaration]
    const int fd = CpuFeatures_OpenFile("/var/run/dmesg.boot");
                   ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1337:7: error: use of undeclared identifier 'StackLineReader'
      StackLineReader reader;
      ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1338:7: warning: implicit declaration of function 'StackLineReader_Initialize' is invalid in C99 [-Wimplicit-function-declaration]
      StackLineReader_Initialize(&reader, fd);
      ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1338:35: error: use of undeclared identifier 'reader'
      StackLineReader_Initialize(&reader, fd);
                                  ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1340:15: error: unknown type name 'LineResult'
        const LineResult result = StackLineReader_NextLine(&reader);
              ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1340:35: warning: implicit declaration of function 'StackLineReader_NextLine' is invalid in C99 [-Wimplicit-function-declaration]
        const LineResult result = StackLineReader_NextLine(&reader);
                                  ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1340:61: error: use of undeclared identifier 'reader'
        const LineResult result = StackLineReader_NextLine(&reader);
                                                            ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1341:13: warning: implicit declaration of function 'CpuFeatures_StringView_StartsWith' is invalid in C99 [-Wimplicit-function-declaration]
        if (CpuFeatures_StringView_StartsWith(result.line,
            ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1342:47: warning: implicit declaration of function 'str' is invalid in C99 [-Wimplicit-function-declaration]
                                              str("  Features=")) ||
                                              ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1354:15: warning: implicit declaration of function 'CpuFeatures_StringView_HasWord' is invalid in C99 [-Wimplicit-function-declaration]
          if (CpuFeatures_StringView_HasWord(value, "SSE"))
              ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1354:46: error: use of undeclared identifier 'value'
          if (CpuFeatures_StringView_HasWord(value, "SSE"))
                                             ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1356:46: error: use of undeclared identifier 'value'
          if (CpuFeatures_StringView_HasWord(value, "SSE2"))
                                             ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1358:46: error: use of undeclared identifier 'value'
          if (CpuFeatures_StringView_HasWord(value, "SSE3"))
                                             ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1360:46: error: use of undeclared identifier 'value'
          if (CpuFeatures_StringView_HasWord(value, "SSSE3"))
                                             ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1362:46: error: use of undeclared identifier 'value'
          if (CpuFeatures_StringView_HasWord(value, "SSE4.1"))
                                             ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1364:46: error: use of undeclared identifier 'value'
          if (CpuFeatures_StringView_HasWord(value, "SSE4.2"))
                                             ^
/wrkdirs/overlays/devel/devel/volk/work/volk-2.5.0/cpu_features/src/cpuinfo_x86.c:1370:5: warning: implicit declaration of function 'CpuFeatures_CloseFile' is invalid in C99 [-Wimplicit-function-declaration]
    CpuFeatures_CloseFile(fd);
    ^
7 warnings and 11 errors generated.

mldulaney · 2021-06-25T22:26:30Z

edit: @vishwin beat me to it.

gchatelet · 2021-06-30T10:17:38Z

Thx @mldulaney and @vishwin ! We're waiting to have at least one FreeBSD CI before moving on with this patch.
Stay tuned!

Mizux · 2021-06-30T17:08:11Z

@gchatelet FYI:

    default: /usr/home/vagrant/project/test/cpuinfo_x86_test.cc
    default: :
    default: 762:3: error: use of undeclared identifier 'fs'
    default:   fs.CreateFile("/var/run/dmesg.boot", R"(
    default:   ^
    default: /usr/home/vagrant/project/test/cpuinfo_x86_test.cc:837:3: error: use of undeclared identifier 'fs'
    default:   fs.CreateFile("/var/run/dmesg.boot", R"(
    default:   ^
    default: 2 errors generated.
    default: *** Error code 1
    default: 
    default: Stop.
    default: make[2]: stopped in /usr/home/vagrant/project/build
    default: *** Error code 1
    default: 
    default: Stop.
    default: make[1]: stopped in /usr/home/vagrant/project/build
    default: *** Error code 1
    default: 
    default: Stop.
    default: make: stopped in /usr/home/vagrant/project/build

ref: https://github.com/google/cpu_features/runs/2954585917?check_suite_focus=true#step:5:902

mldulaney · 2021-06-30T18:02:56Z

-- Looking for getauxval - not found
CMake Error at cpu_features/CMakeLists.txt:196 (message):
CMake step for googletest failed: No such file or directory

-- Configuring incomplete, errors occurred!

evadot · 2021-06-30T19:41:10Z

Not familiar with this lib but you should never parse dmesg.boot or use some sysctl to obtain this info.
You should use elf_aux_info with AT_HWCAP/AT_HWCAP2.

gchatelet · 2021-07-01T08:35:28Z

Not familiar with this lib but you should never parse dmesg.boot or use some sysctl to obtain this info.
You should use elf_aux_info with AT_HWCAP/AT_HWCAP2.

Thx a lot @evadot. This is exactly what I was looking for. From the documentation: The elf_aux_info() function appeared in FreeBSD 12.0.. How would I get this information prior to FreeBSD 12?

evadot · 2021-07-01T08:37:50Z

Not familiar with this lib but you should never parse dmesg.boot or use some sysctl to obtain this info.
You should use elf_aux_info with AT_HWCAP/AT_HWCAP2.

Thx a lot @evadot. This is exactly what I was looking for. From the documentation: The elf_aux_info() function appeared in FreeBSD 12.0.. How would I get this information prior to FreeBSD 12?

FreeBSD 11 will be EOL in september so I wouldn't bother.

evadot · 2021-07-01T08:38:01Z

Not familiar with this lib but you should never parse dmesg.boot or use some sysctl to obtain this info.
You should use elf_aux_info with AT_HWCAP/AT_HWCAP2.

Thx a lot @evadot. This is exactly what I was looking for. From the documentation: The elf_aux_info() function appeared in FreeBSD 12.0.. How would I get this information prior to FreeBSD 12?

FreeBSD 11 will be EOL in september so I wouldn't bother.

gchatelet · 2021-07-01T09:08:05Z

@evadot let me know if I understand this correctly.
From these lines here and here, only AT_HWCAP is set (AT_HWCAP2 is set to zero).

Now AT_HWCAP for x86 seems to return cpu_features which AFAIU can be interpreted with one of the CPUID_* masks here. This gives me access to XMM, MMX, SSE and SSE2. To retrieve cpu features for SSE3, SSSE3, SSE4.1 and SSE4.2 I'd need to get cpu_feature2 which - it seems - is not available through AT_HWCAP2. Am I missing something?

evadot · 2021-07-01T09:49:32Z

@evadot let me know if I understand this correctly.
From these lines here and here, only AT_HWCAP is set (AT_HWCAP2 is set to zero).

Now AT_HWCAP for x86 seems to return cpu_features which AFAIU can be interpreted with one of the CPUID_* masks here. This gives me access to XMM, MMX, SSE and SSE2. To retrieve cpu features for SSE3, SSSE3, SSE4.1 and SSE4.2 I'd need to get cpu_feature2 which - it seems - is not available through AT_HWCAP2. Am I missing something?

That's for the linuxulator.
Apparently we do not expose AT_HWCAP on x86 but only for powerpc*, arm* and riscv.
You should use the cpuid directly on amd64, you can look at https://cgit.freebsd.org/src/tree/lib/csu/amd64/reloc.c for an example on how to do this.

gchatelet · 2021-07-01T14:14:27Z

@evadot let me know if I understand this correctly.
From these lines here and here, only AT_HWCAP is set (AT_HWCAP2 is set to zero).
Now AT_HWCAP for x86 seems to return cpu_features which AFAIU can be interpreted with one of the CPUID_* masks here. This gives me access to XMM, MMX, SSE and SSE2. To retrieve cpu features for SSE3, SSSE3, SSE4.1 and SSE4.2 I'd need to get cpu_feature2 which - it seems - is not available through AT_HWCAP2. Am I missing something?

That's for the linuxulator.
Apparently we do not expose AT_HWCAP on x86 but only for powerpc*, arm* and riscv.
You should use the cpuid directly on amd64, you can look at https://cgit.freebsd.org/src/tree/lib/csu/amd64/reloc.c for an example on how to do this.

Thx for your answer @evadot. This project already uses the cpuid instruction to query the presence/absence of some features at the cpu level, but we also need to know if the OS preserves these vector registers across context switches. For AVX enabled CPUs the OS has the possibility to use the XCR0 register. Then using cpuid is all you need.
Now the code here deals with pre-AVX cpus (Atom, Westmere, ...) where there is no way to ask the CPU whether the OS will save and restore vector registers across context switches. We have to query the OS to get this information. As far as I understand, the only way to get this information on FreeBSD is to parse /var/run/dmesg.boot. Let me know if you see another way.

An interesting sidenote, for Darwin - which is FreeBSD based - the OS disables AVX512 registers save/restore by default and enables them right after the first fault. Thus querying the CPU for AVX512 OS support fails even though it works (source).

test/cpuinfo_x86_test.cc

src/cpuinfo_x86.c

gchatelet · 2021-07-02T13:36:33Z

As discussed, let's submit this as-is to repair the build. I'll address the TODO in a subsequent PR.

mldulaney · 2021-07-03T15:01:51Z

Thanks!

gchatelet added the enhancement New feature or request label Jun 25, 2021

gchatelet requested a review from Mizux June 25, 2021 07:59

Mizux reviewed Jun 25, 2021

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gchatelet mentioned this pull request Jun 25, 2021

Support Freebsd #159

Closed

vishwin reviewed Jun 25, 2021

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Add support for FreeBSD on x86

c86c2a9

gchatelet force-pushed the freebsd branch from 504ea1d to c86c2a9 Compare June 30, 2021 13:23

Fix

bd2c2d1

Add missing fs variable

c434cf4

Mizux reviewed Jul 1, 2021

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gchatelet added 4 commits July 2, 2021 12:15

Fix assignment instead of comparison

ebe93a2

Fix missing fake file system in tests

d3d9555

Also make line non const so it can be changed.

6ceeefc

cast away constness in the meantime

2fba62f

Correct casting (hopefuly)

2f8c741

Mizux approved these changes Jul 2, 2021

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gchatelet merged commit 1199437 into master Jul 2, 2021

gchatelet deleted the freebsd branch July 2, 2021 13:37

jdemel mentioned this pull request Dec 22, 2021

Disabling VOLK_CPU_FEATURES causes tests to fail on 2.5.0 gnuradio/volk#484

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gchatelet added this to the v0.7.0 milestone Mar 8, 2022

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Add support for FreeBSD on x86 #163

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Add support for FreeBSD on x86 #163

Add support for FreeBSD on x86 #163

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