[Buildroot] Crosstool-ng external toolchain with BR2_ROOTFS_MERGED_USR

[Buildroot] Crosstool-ng external toolchain with BR2_ROOTFS_MERGED_USR

[Charlie Jenkins]

I am trying to use a crosstool-ng build toolchain in Buildroot with the
BR2_ROOTFS_MERGED_USR option enabled. However, crosstool-ng installs
the sysroot libs at /lib instead /usr/lib as BR2_ROOTFS_MERGED_USR
expects. I am not sure what the best solution for this is. Should
BR2_ROOTFS_MERGED_USR be ignored for toolchain packages when an external
toolchain is being used?

My crosstool-ng config is:
CT_CONFIG_VERSION="4"
CT_ARCH_RISCV=y
# CT_DEMULTILIB is not set
CT_ARCH_USE_MMU=y
CT_ARCH_64=y
CT_ARCH_ARCH="rv64gc"
CT_KERNEL_LINUX=y
CT_CC_LANG_CXX=y
CT_DEBUG_GDB=y
# CT_GDB_CROSS_PYTHON is not set
# CT_GDB_GDBSERVER is not set

My buildroot config is:
BR2_riscv=y
BR2_TOOLCHAIN_EXTERNAL=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM=y
BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y
BR2_TOOLCHAIN_EXTERNAL_URL="<path to built crosstool-ng toolchain>"
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_PREFIX="$(ARCH)-unknown-linux-gnu"
BR2_TOOLCHAIN_EXTERNAL_HEADERS_6_11=y
BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
# BR2_TOOLCHAIN_EXTERNAL_INET_RPC is not set
# BR2_STRIP_strip is not set
BR2_ROOTFS_MERGED_USR=y

- Charlie

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Re: [Buildroot] Crosstool-ng external toolchain with BR2_ROOTFS_MERGED_USR

[Charlie Jenkins]

On Sun, Mar 09, 2025 at 10:52:53PM -0700, Charlie Jenkins wrote:
> I am trying to use a crosstool-ng build toolchain in Buildroot with the
> BR2_ROOTFS_MERGED_USR option enabled. However, crosstool-ng installs
> the sysroot libs at /lib instead /usr/lib as BR2_ROOTFS_MERGED_USR
> expects. I am not sure what the best solution for this is. Should
> BR2_ROOTFS_MERGED_USR be ignored for toolchain packages when an external
> toolchain is being used?

I meant to add more information about the failure...

Because crosstool-ng installs the libs at /lib instead of /usr/lib, the
libraries end up getting symlinked into nothingness. For example:

$ ls -l ./output/host/riscv64-buildroot-linux-gnu/sysroot/usr/lib/libm.so
lrwxrwxrwx 1 charlie rvs 6 Mar  9 22:58 ./output/host/riscv64-buildroot-linux-gnu/sysroot/usr/lib/libm.so -> ../../

> 
> My crosstool-ng config is:
> CT_CONFIG_VERSION="4"
> CT_ARCH_RISCV=y
> # CT_DEMULTILIB is not set
> CT_ARCH_USE_MMU=y
> CT_ARCH_64=y
> CT_ARCH_ARCH="rv64gc"
> CT_KERNEL_LINUX=y
> CT_CC_LANG_CXX=y
> CT_DEBUG_GDB=y
> # CT_GDB_CROSS_PYTHON is not set
> # CT_GDB_GDBSERVER is not set
> 
> My buildroot config is:
> BR2_riscv=y
> BR2_TOOLCHAIN_EXTERNAL=y
> BR2_TOOLCHAIN_EXTERNAL_CUSTOM=y
> BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y
> BR2_TOOLCHAIN_EXTERNAL_URL="<path to built crosstool-ng toolchain>"
> BR2_TOOLCHAIN_EXTERNAL_CUSTOM_PREFIX="$(ARCH)-unknown-linux-gnu"
> BR2_TOOLCHAIN_EXTERNAL_HEADERS_6_11=y
> BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
> # BR2_TOOLCHAIN_EXTERNAL_INET_RPC is not set
> # BR2_STRIP_strip is not set
> BR2_ROOTFS_MERGED_USR=y
> 
> - Charlie
> 
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Re: [Buildroot] Crosstool-ng external toolchain with BR2_ROOTFS_MERGED_USR

[Charlie Jenkins]

On Sun, Mar 09, 2025 at 11:00:57PM -0700, Charlie Jenkins wrote:
> On Sun, Mar 09, 2025 at 10:52:53PM -0700, Charlie Jenkins wrote:
> > I am trying to use a crosstool-ng build toolchain in Buildroot with the
> > BR2_ROOTFS_MERGED_USR option enabled. However, crosstool-ng installs
> > the sysroot libs at /lib instead /usr/lib as BR2_ROOTFS_MERGED_USR
> > expects. I am not sure what the best solution for this is. Should
> > BR2_ROOTFS_MERGED_USR be ignored for toolchain packages when an external
> > toolchain is being used?
> 
> I meant to add more information about the failure...
> 
> Because crosstool-ng installs the libs at /lib instead of /usr/lib, the
> libraries end up getting symlinked into nothingness. For example:
> 
> $ ls -l ./output/host/riscv64-buildroot-linux-gnu/sysroot/usr/lib/libm.so
> lrwxrwxrwx 1 charlie rvs 6 Mar  9 22:58 ./output/host/riscv64-buildroot-linux-gnu/sysroot/usr/lib/libm.so -> ../../

I believed I fixed the problem here:

https://lore.kernel.org/buildroot/20250310-fix_external_toolchains-v1-1-446f48af7cf7@rivosinc.com/T/#u

- Charlie

> 
> > 
> > My crosstool-ng config is:
> > CT_CONFIG_VERSION="4"
> > CT_ARCH_RISCV=y
> > # CT_DEMULTILIB is not set
> > CT_ARCH_USE_MMU=y
> > CT_ARCH_64=y
> > CT_ARCH_ARCH="rv64gc"
> > CT_KERNEL_LINUX=y
> > CT_CC_LANG_CXX=y
> > CT_DEBUG_GDB=y
> > # CT_GDB_CROSS_PYTHON is not set
> > # CT_GDB_GDBSERVER is not set
> > 
> > My buildroot config is:
> > BR2_riscv=y
> > BR2_TOOLCHAIN_EXTERNAL=y
> > BR2_TOOLCHAIN_EXTERNAL_CUSTOM=y
> > BR2_TOOLCHAIN_EXTERNAL_DOWNLOAD=y
> > BR2_TOOLCHAIN_EXTERNAL_URL="<path to built crosstool-ng toolchain>"
> > BR2_TOOLCHAIN_EXTERNAL_CUSTOM_PREFIX="$(ARCH)-unknown-linux-gnu"
> > BR2_TOOLCHAIN_EXTERNAL_HEADERS_6_11=y
> > BR2_TOOLCHAIN_EXTERNAL_CUSTOM_GLIBC=y
> > # BR2_TOOLCHAIN_EXTERNAL_INET_RPC is not set
> > # BR2_STRIP_strip is not set
> > BR2_ROOTFS_MERGED_USR=y
> > 
> > - Charlie
> > 
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