[PATCH] kbuild: avoid scripts/kallsyms parsing /dev/null

[PATCH] kbuild: avoid scripts/kallsyms parsing /dev/null

[Masahiro Yamada]

On macOS, getline() sets ENOTTY to errno if it is requested to read
from /dev/null.

If this is worth fixing, I would rather pass an empty file to
scripts/kallsyms instead of adding the ugly #ifdef __APPLE__.

Fixes: c442db3f49f2 ("kbuild: remove PROVIDE() for kallsyms symbols")
Reported-by: Daniel Gomez <da.gomez@samsung.com>
Closes: https://lore.kernel.org/all/20240807-macos-build-support-v1-12-4cd1ded85694@samsung.com/
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

 scripts/link-vmlinux.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
index f7b2503cdba9..41c68ae3415d 100755
--- a/scripts/link-vmlinux.sh
+++ b/scripts/link-vmlinux.sh
@@ -219,7 +219,8 @@ kallsymso=
 strip_debug=
 
 if is_enabled CONFIG_KALLSYMS; then
-	kallsyms /dev/null .tmp_vmlinux0.kallsyms
+	truncate -s0 .tmp_vmlinux.kallsyms0.syms
+	kallsyms .tmp_vmlinux.kallsyms0.syms .tmp_vmlinux0.kallsyms
 fi
 
 if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then
-- 
2.43.0

Re: [PATCH] kbuild: avoid scripts/kallsyms parsing /dev/null

[Nicolas Schier]

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On Thu 08 Aug 2024 03:03:00 GMT, Masahiro Yamada wrote:
> On macOS, getline() sets ENOTTY to errno if it is requested to read
> from /dev/null.
> 
> If this is worth fixing, I would rather pass an empty file to
> scripts/kallsyms instead of adding the ugly #ifdef __APPLE__.
> 
> Fixes: c442db3f49f2 ("kbuild: remove PROVIDE() for kallsyms symbols")
> Reported-by: Daniel Gomez <da.gomez@samsung.com>
> Closes: https://lore.kernel.org/all/20240807-macos-build-support-v1-12-4cd1ded85694@samsung.com/
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
>  scripts/link-vmlinux.sh | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index f7b2503cdba9..41c68ae3415d 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -219,7 +219,8 @@ kallsymso=
>  strip_debug=
>  
>  if is_enabled CONFIG_KALLSYMS; then
> -	kallsyms /dev/null .tmp_vmlinux0.kallsyms
> +	truncate -s0 .tmp_vmlinux.kallsyms0.syms
> +	kallsyms .tmp_vmlinux.kallsyms0.syms .tmp_vmlinux0.kallsyms
>  fi
>  
>  if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then
> -- 
> 2.43.0
> 
> 

Thanks!  I definitely support moving special MacOS support from source 
code into scripts and Makefiles.

Might you want to add a comment to truncate, to prevent accidental 
attempts to revert/refactor this?

Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>

Kind regards,
Nicolas

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Re: [PATCH] kbuild: avoid scripts/kallsyms parsing /dev/null

[Daniel Gomez]

On Thu, Aug 08, 2024 at 03:03:00AM GMT, Masahiro Yamada wrote:
> On macOS, getline() sets ENOTTY to errno if it is requested to read
> from /dev/null.
> 
> If this is worth fixing, I would rather pass an empty file to
> scripts/kallsyms instead of adding the ugly #ifdef __APPLE__.
> 
> Fixes: c442db3f49f2 ("kbuild: remove PROVIDE() for kallsyms symbols")
> Reported-by: Daniel Gomez <da.gomez@samsung.com>
> Closes: https://lore.kernel.org/all/20240807-macos-build-support-v1-12-4cd1ded85694@samsung.com/
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
> ---
> 
>  scripts/link-vmlinux.sh | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh
> index f7b2503cdba9..41c68ae3415d 100755
> --- a/scripts/link-vmlinux.sh
> +++ b/scripts/link-vmlinux.sh
> @@ -219,7 +219,8 @@ kallsymso=
>  strip_debug=
>  
>  if is_enabled CONFIG_KALLSYMS; then
> -	kallsyms /dev/null .tmp_vmlinux0.kallsyms
> +	truncate -s0 .tmp_vmlinux.kallsyms0.syms

This looks nicer. Thanks for a quick alternative!

I prefer self explained commands and use the larger argument if available:
	truncate --size=0 .tmp_vmlinux.kallsyms0.syms

But other than that, LGTM.

Reviewed-by: Daniel Gomez <da.gomez@samsung.com>

> +	kallsyms .tmp_vmlinux.kallsyms0.syms .tmp_vmlinux0.kallsyms
>  fi
>  
>  if is_enabled CONFIG_KALLSYMS || is_enabled CONFIG_DEBUG_INFO_BTF; then
> -- 
> 2.43.0
>