I am trying to build a arm RPI4 crosscompiler and toolchain on cygwin on windows 10 with ctosstool-ng-1.24.0

The process works fine generating a arm RPI4 toolchain from ubuntu 20.4 host but fails on windows 10

The Prebuilt Windows Toolchain for Raspberry Pi have gold linker issue that fails to resolve gtk-3 and gdk-3 dependencies libs on windows. so I am trying to see if a newly generated one will resolve the problem.

ctosstool-ng build fails on cygwin for armv8-rpi3-linux-gnueabihf consistently with a flurry of

[ERROR]      /usr/include/sys/features.h:322:5: error: "_FORTIFY_SOURCE" is not defined, evaluates to 0 [-Werror=undef]

followed by

[EXTRA]      Installing C library start files
[ERROR]      ../include/link.h:43:57: error: unknown type name 'Lmid_t'; did you mean 'pid_t'?
[ERROR]      ../sysdeps/posix/dl-fileid.h:27:5: error: unknown type name 'ino64_t'
[ERROR]      ../sysdeps/posix/dl-fileid.h:35:17: error: storage size of 'st' isn't known
[ERROR]      ../sysdeps/posix/dl-fileid.h:37:37: error: '_STAT_VER' undeclared (first use in this function)
[ERROR]      /usr/include/cygwin/core_dump.h:19:10: fatal error: windows.h: No such file or directory
[ERROR]      /usr/include/cygwin/core_dump.h:19:10: fatal error: windows.h: No such file or directory
[ERROR]      make[3]: *** [../Makerules:287: /cygdrive/c/repo/ctng124/bld/.build/arm-unknown-linux-gnueabihf/build/build-libc-startfiles/multilib/tlsdesc.h] Error 1
[ERROR]      make[3]: *** Waiting for unfinished jobs....
[ERROR]      make[3]: *** [../Makerules:287: /cygdrive/c/repo/ctng124/bld/.build/arm-unknown-linux-gnueabihf/build/build-libc-startfiles/multilib/tcb-offsets.h] Error 1
[ERROR]      /usr/include/cygwin/core_dump.h:19:10: fatal error: windows.h: No such file or directory
[ERROR]      make[3]: *** [../Makerules:287: /cygdrive/c/repo/ctng124/bld/.build/arm-unknown-linux-gnueabihf/build/build-libc-startfiles/multilib/rtld-global-offsets.h] Error 1
[ERROR]      make[2]: *** [Makefile:258: csu/subdir_lib] Error 2
[ERROR]      make[1]: *** [Makefile:9: csu/subdir_lib] Error 2
[ERROR]  /
[ERROR]  >>
[ERROR]  >>  Build failed in step 'Building for multilib 1/1: '''
[ERROR]  >>        called in step 'Installing C library headers & start files'
[ERROR]  >>        called in step '(top-level)'
[ERROR]  >>
[ERROR]  >>  Error happened in: CT_DoExecLog[scripts/functions@376]
[ERROR]  >>        called from: glibc_backend_once[scripts/build/libc/glibc.sh@374]
[ERROR]  >>        called from: CT_IterateMultilibs[scripts/functions@1586]
[ERROR]  >>        called from: glibc_backend[scripts/build/libc/glibc.sh@74]
[ERROR]  >>        called from: glibc_start_files[scripts/build/libc/glibc.sh@38]
[ERROR]  >>        called from: do_libc_start_files[scripts/build/libc.sh@28]
[ERROR]  >>        called from: main[scripts/crosstool-NG.sh@696]
[ERROR]  >>
[ERROR]  >>  For more info on this error, look at the file: 'build.log'
[ERROR]  >>  There is a list of known issues, some with workarounds, in:
[ERROR]  >>      https://crosstool-ng.github.io/docs/known-issues/
[ERROR]  >>
[ERROR]  >>  If you feel this is a bug in crosstool-NG, report it at:
[ERROR]  >>      https://github.com/crosstool-ng/crosstool-ng/issues/
[ERROR]  >>
[ERROR]  >>  Make sure your report includes all the information pertinent to this issue.
[ERROR]  >>  Read the bug reporting guidelines here:
[ERROR]  >>      http://crosstool-ng.github.io/support/
[ERROR]  /
[ERROR]  (elapsed: 130:50.55)
[131:02] / make: *** [ct-ng:261: build] Error 2

I have tried cygwin gcc version 9.3 and 11.3 and also, under menuconfig, glib2.28 and glib2.24. All of them fail at the "libc_start_files" step after installing kernel_headers.

Steps followed from :

$ ../configure --prefix=<install-dir>
$ make
$ make install
$ ./ct-ng armv8-rpi3-linux-gnueabihf
$ ./ct-ng menuconfig (choose glib 2.28)
$ ./ct-ng build

Link to : build logs .config make and make-install logs

If anyone has else succeeded on building this on windows host please share your steps/configuration.

===[UPDATE 1] ===

It looks like c:/cygwin64//usr/include cygwin env is being included in the compiler options. I located ac_cv_env_CPPFLAGS_value=-Ic:/cygwin64//usr/include in build/build-libc-startfiles/multilib/config.cache. But not sure if thats the one causing linux files into cygwin64 includes.

gawk -f ../scripts/gen-as-const.awk ../sysdeps/arm/tlsdesc.sym |
arm-unknown-linux-gnueabihf-gcc  -O2 -D_FORTIFY_SOURCE=0  
-mlittle-endian   -mcpu=cortex-a53  -mfpu=neon-vfpv4 -mhard-float    
-S -o /cygdrive/c/repo/ctng124/bld/.build/arm-unknown-linux-gnueabihf/build/build-libc-startfiles/multilib/tlsdesc.hT3 
-std=gnu11 -fgnu89-inline  -O2 -Wall -Wundef -Wwrite-strings 
-fmerge-all-constants -fno-stack-protector -frounding-math -g 
-Wstrict-prototypes -Wold-style-definition -fno-math-errno     
-ftls-model=initial-exec   

-U_FORTIFY_SOURCE -Ic:/cygwin64//usr/include  

< rest pf of the includes are from under the .build dir >
... -I.. -I../libio -I. -nostdinc -isystem  .... 
-DTOP_NAMESPACE=glibc       -DGEN_AS_CONST_HEADERS -x c -   
-MD -MP -MF /cygdrive/c/repo/ctng124/bld/.build/arm-unknown-linux-gnueabihf/build/build-libc-startfiles/multilib/tlsdesc.h.dT 
-MT '/cygdrive/c/repo/ctng124/bld/.build/arm-unknown-linux-gnueabihf/build/build-libc-startfiles/multilib/tlsdesc.h.d 
/cygdrive/c/repo/ctng124/bld/.build/arm-unknown-linux-gnueabihf/build/build-libc-startfiles/multilib/tlsdesc.h'

Also its not clear how these propagate from the root build directory into the component build/compiler options.

Any suggestion to track/debug the compiler options will be most helpful.

===

Has anyone encountered these errors?

What could be causing them?

Please share any experience you have on the above.