{"id":2903,"date":"2021-03-27T14:15:17","date_gmt":"2021-03-27T21:15:17","guid":{"rendered":"https:\/\/rglinuxtech.com\/?p=2903"},"modified":"2021-03-30T15:41:15","modified_gmt":"2021-03-30T22:41:15","slug":"compiler-fun-with-clang-kernel-nvidia-and-vmware","status":"publish","type":"post","link":"https:\/\/rglinuxtech.com\/?p=2903","title":{"rendered":"Compiler – Fun with CLANG – Kernel, NVIDIA, and VMware…"},"content":{"rendered":"

I have been carrying out some preliminary tests to see how feasible it is to compile the Linux Kernel, and NVIDIA drivers, and VMware, using the ‘alternative’ to GCC – CLANG<\/strong>..<\/p>\n

The kernel compile is relatively easy, and well documented:<\/p>\n

# make CC=clang HOSTCC=clang -j8 (for a 4-core system)<\/span><\/strong><\/code><\/p>\n

The compile seems to be slower<\/em> than GCC, but completes without problems, and boots\/runs OK:<\/p>\n

# uname -a<\/span><\/strong>
\nLinux rg400g4 5.11.10 #1 SMP Fri Mar 26 20:56:15 PDT 2021 x86_64 x86_64 x86_64 GNU\/Linux<\/span><\/strong><\/code><\/p>\n

I was able to get the latest NVIDIA driver to compile using:<\/p>\n

# export CC=clang<\/strong><\/span>
\n# export CXX=clang++<\/strong><\/span>
\n# .\/NVIDIA-Linux-x86_64-460.67.run -s --install-libglvnd<\/strong><\/span><\/code><\/p>\n

This worked, but gave a rather confused warning:<\/p>\n

WARNING: Ignoring CC version mismatch:<\/strong><\/span>
\nThe kernel was built with clang version 12.0.0 (Fedora<\/strong><\/span>
\n12.0.0-0.2.rc1.fc34), GNU ld version 2.35.1-41.fc34, but the<\/strong><\/span>
\ncurrent compiler version is clang version 12.0.0 (Fedora<\/strong><\/span>
\n12.0.0-0.2.rc1.fc34).<\/strong><\/span><\/code><\/p>\n

Once again, the compile seemed to take longer than GCC, but completed successfully:<\/p>\n

# lsmod |grep nv<\/strong><\/span>
\nnvidia_drm 61440 0<\/strong><\/span>
\nnvidia_modeset 1208320 1 nvidia_drm<\/strong><\/span>
\nnvidia 34009088 1 nvidia_modeset<\/strong><\/span>
\ndrm_kms_helper 212992 1 nvidia_drm<\/strong><\/span>
\ndrm<\/strong><\/span><\/code><\/p>\n

A manual compile from extracted !\/NVIDIA-Linux-x86_64-460.67.run\/kernel<\/span><\/strong> showed a large number of ‘warnings’:<\/p>\n

# export CC=clang<\/span><\/strong>
\n# export CXX=clang++<\/span><\/strong>
\n# make<\/span><\/strong>
\n.............<\/span><\/strong>
\n\/home\/rgadsdon\/NVIDIA-Linux-x86_64-460.67\/kernel\/nvidia-uvm\/uvm_map_external.c:104:59: warning: implicit conversion from enumeration type 'const UvmGpuCachingType' to different enumeration type 'UvmRmGpuCachingType' [-Wenum-conversion]<\/span><\/strong>
\npte_buffer->mapping_info.cachingType = map_rm_params->caching_type;<\/span><\/strong>
\n~ ~~~~~~~~~~~~~~~^~~~~~~~~~~~<\/span><\/strong>
\n<< repeated.. >><\/span><\/strong>
\n.............<\/span><\/strong><\/code><\/p>\n

VMware<\/strong> was interesting, and the usual vmware-modconfig<\/strong><\/span>…. was confused, and failed as it could not find gcc, despite prior CC\/HOSTCC exports to clang etc:
\n# vmware-modconfig --console --install-all <\/strong><\/span>
\n[AppLoader] GLib does not have GSettings support.<\/strong><\/span>
\nFailed to get gcc information....<\/strong><\/span><\/code><\/p>\n

This was due to the fact that it was still trying to find gcc, and was failing, as gcc was not specified..<\/p>\n

(Just to confirm, the Fedora 34<\/em> gcc version\u00a0 – gcc 11<\/strong>.. – does<\/span> work OK with the vmware-modconfig<\/strong><\/span> command, when compiling with gcc..)<\/p>\n

The simplest workaround for this is to use the patched vmmon<\/strong>\/vmnet<\/strong> source in the (current) vmware-host-modules-workstation-16.1.0<\/span><\/strong> directory, and run:
\n# make CC=clang HOSTCC=clang<\/strong><\/span> followed by (su) #make install<\/span><\/strong> . I found that in this case separate # export CC=clang<\/strong><\/span> and # export HOSTCC=clang<\/span><\/strong> followed by # make<\/strong><\/span> failed, but the inline command did work..<\/p>\n

The resulting system booted OK, and NVIDIA and VMware both ran successfully.
\nI was not able to detect any obvious performance issues, but the system was not stress tested at this time….\u00a0\u00a0 This was an interesting exercise, but I am going to stay with gcc<\/strong>, for the time being..<\/p>\n

As a historical note, this was the first time I had compiled the Kernel without using ‘vanilla’ GCC, since the days – many years ago – when I had to use EGCS…<\/p>\n

Robert Gadsdon.\u00a0 March 27th, 2021.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

I have been carrying out some preliminary tests to see how feasible it is to compile the Linux Kernel, and NVIDIA drivers, and VMware, using the ‘alternative’ to GCC – CLANG.. The kernel compile is relatively easy, and well documented: # make CC=clang HOSTCC=clang -j8 (for a 4-core system) The compile seems to be slower than GCC, …<\/span> Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"footnotes":""},"categories":[2377,5,10,1617,14,15,18,19,20,1535,25],"tags":[2378,2036,2379,1173,277,1175,402],"class_list":["post-2903","post","type-post","status-publish","format-standard","hentry","category-clang","category-compilation","category-fedora","category-gcc","category-kernel","category-linux-2","category-nvidia","category-opinion","category-performance-2","category-quirks","category-vmware","tag-clang","tag-compile-tests","tag-gcc-alternative","tag-kernel","tag-nvidia-2","tag-success","tag-vmware-2"],"_links":{"self":[{"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=\/wp\/v2\/posts\/2903","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2903"}],"version-history":[{"count":9,"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=\/wp\/v2\/posts\/2903\/revisions"}],"predecessor-version":[{"id":2912,"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=\/wp\/v2\/posts\/2903\/revisions\/2912"}],"wp:attachment":[{"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2903"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2903"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/rglinuxtech.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2903"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}