30 Apr
2019
30 Apr
'19
5:13 p.m.
On 4/30/19 10:04 AM, Rich Felker wrote:
On Tue, Apr 30, 2019 at 03:53:18PM +0000, Vineet Gupta
wrote:
Sorry I added you as a subject matter expert but didn't provide enough context.
The original issue [1] was perf failing to build on ARC due to perf tools needing
a copy of unistd.h but this thread [2] was a small side issue of auto-detecting
libc variaint in perf tools where despite uClibc tools, glibc is declared to be
detected, due to uClibc's historical hack of defining __GLIBC__. So __GLIBC__ is
not sufficient (and probably not the right interface to begin wtih) to ensure glibc.
[1] http://lists.infradead.org/pipermail/linux-snps-arc/2019-April/005676.html
[2] http://lists.infradead.org/pipermail/linux-snps-arc/2019-April/005684.html
On 4/29/19 6:18 PM, Arnaldo Carvalho de Melo
wrote:
Right you are. Per the big fat comment right above that code, this gross hack in
uclibc is unavoidable as applications tend to rely on that define.
So a better fix would be to check for various !GLIBC libs explicitly.
#ifdef __UCLIBC__
#elseif defined __MUSL__
....
Not pretty from app usage pov, but that seems to be the only sane way of doing it.
What are you trying to achieve? I was just CC'd and I'm missing the
context. >
Auto-detecting system features:
> ... dwarf: [ OFF ]
> ... dwarf_getlocations: [ OFF ]
> ... glibc: [ on ]
Not related to current issue, this run uses a uClibc toolchain and yet it is
detecting glibc - doesn't seem right to me.
Ok, I'll improve that, I think
it just tries to detect a libc, yeah,
see:
[acme@quaco linux]$ cat tools/build/feature/test-glibc.c
// SPDX-License-Identifier: GPL-2.0
#include <stdlib.h>
#if !defined(__UCLIBC__)
#include <gnu/libc-version.h>
#else
#define XSTR(s) STR(s)
#define STR(s) #s
#endif
int main(void)
{
#if !defined(__UCLIBC__)
const char *version = gnu_get_libc_version();
#else
const char *version = XSTR(__GLIBC__) "." XSTR(__GLIBC_MINOR__);
#endif
return (long)version;
}
[acme@quaco linux]$
[perfbuilder@59ca4b424ded /]$ grep __GLIBC__
/arc_gnu_2017.09-rc2_prebuilt_uclibc_le_arc700_linux_install/arc-snps-linux-uclibc/sysroot/usr/include/*.h
/arc_gnu_2017.09-rc2_prebuilt_uclibc_le_arc700_linux_install/arc-snps-linux-uclibc/sysroot/usr/include/features.h:
The macros `__GNU_LIBRARY__', `__GLIBC__', and `__GLIBC_MINOR__' are
/arc_gnu_2017.09-rc2_prebuilt_uclibc_le_arc700_linux_install/arc-snps-linux-uclibc/sysroot/usr/include/features.h:#define __GLIBC__ 2
/arc_gnu_2017.09-rc2_prebuilt_uclibc_le_arc700_linux_install/arc-snps-linux-uclibc/sysroot/usr/include/features.h: ((__GLIBC__
<< 16) + __GLIBC_MINOR__ >= ((maj) << 16) + (min))
[perfbuilder@59ca4b424ded /]$
Isn't that part of uClibc?