Hi, I've been experimenting with musl-libc Gentoo systems. I used the HEAD of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/btrfs-progs.git
I found that btrfs-progs does not compile with musl-libc, for a few reasons: * It makes use of the private glibc __always_inline macro. * Various headers that should be included are not included: linux/limits.h and limits.h. (for XATTR_SIZE_MAX and PATH_MAX) * backtrace() using execinfo.h is enabled by default; execinfo.h is glibc-specific and thus does not work on other libc's. musl does not support it, and I think uclibc also does not support it. I have worked around the problems in the following way: * Define __always_inline if __glibc__ is not defined. This is arguably the most clean solution. It would be better to simply not use the __always_inline macro (instead, use __attribute__) throughout btrfs-progs, but I was not sure what the developers would prefer. This is currently done in kerncompat.h, but you may want to move that to another file. * Include various headers where required. * If __glibc__ is not defined, define BTRFS_DISABLE_BACKTRACE. Currently the define magic happens in kerncompat, because that also where BTRFS includes execinfo. Personally, I think it would make more sense to always disable backtrace instead of enabling it by default -- but perhaps in a testing phase, enabling it by default in the sensible choice. Attached are the two patches generated with git format-patch. I am aware that this may not be required format for submitting patches -- but please give me some time to get used to the etiquette. :-) Please let me know if musl-libc (or any other libc) is a supported platform, and if so, if and how I can improve on said patches. Regards, Merlijn
From da43021732fab3f70c75f155bded8e5f35fdffe3 Mon Sep 17 00:00:00 2001 From: Merlijn Wajer <merl...@wizzup.org> Date: Sat, 13 Dec 2014 15:07:25 +0100 Subject: [PATCH 1/2] Include headers required for musl-libc. This fixes various compilation errors where PATH_MAX and XATTR_SIZE_MAX were missing. To my knowledge, this should have no bad side effects. --- btrfs-convert.c | 1 + help.c | 1 + mkfs.c | 2 ++ 3 files changed, 4 insertions(+) diff --git a/btrfs-convert.c b/btrfs-convert.c index 02c5e94..7b69a13 100644 --- a/btrfs-convert.c +++ b/btrfs-convert.c @@ -31,6 +31,7 @@ #include <fcntl.h> #include <unistd.h> #include <uuid/uuid.h> +#include <linux/limits.h> #include "ctree.h" #include "disk-io.h" diff --git a/help.c b/help.c index fab942b..56aaf9c 100644 --- a/help.c +++ b/help.c @@ -17,6 +17,7 @@ #include <stdio.h> #include <stdlib.h> #include <string.h> +#include <limits.h> #include "commands.h" #include "utils.h" diff --git a/mkfs.c b/mkfs.c index e10e62d..6343831 100644 --- a/mkfs.c +++ b/mkfs.c @@ -35,6 +35,8 @@ #include <uuid/uuid.h> #include <ctype.h> #include <sys/xattr.h> +#include <limits.h> +#include <linux/limits.h> #include <blkid/blkid.h> #include <ftw.h> #include "ctree.h" -- 2.0.4
From 01d0bfe48dc78b66b6e86d4935d9b9d20194b135 Mon Sep 17 00:00:00 2001 From: Merlijn Wajer <merl...@wizzup.org> Date: Sat, 13 Dec 2014 15:08:43 +0100 Subject: [PATCH 2/2] Disable backtrace and define __always_inline Disable backtrace and define __always_inline when glibc is not used as libc. This, together with some header changes allows btrfs-progs to compile with musl-libc. --- kerncompat.h | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/kerncompat.h b/kerncompat.h index 8afadc8..05823a7 100644 --- a/kerncompat.h +++ b/kerncompat.h @@ -29,6 +29,12 @@ #include <stddef.h> #include <linux/types.h> #include <stdint.h> + +#ifndef __glibc__ +#define BTRFS_DISABLE_BACKTRACE +#define __always_inline __inline __attribute__ ((__always_inline__)) +#endif + #ifndef BTRFS_DISABLE_BACKTRACE #include <execinfo.h> #endif -- 2.0.4
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