Em Mon, Aug 03, 2015 at 01:11:16PM -0300, Arnaldo Carvalho de Melo escreveu:
> > > ERROR: unable to compile ./foo.c
> > > Hint: Check error message shown above.
> > > LLVM 3.7 or newer is required. Which can be found from
> > > http://llvm.org
> > > You may want to try git trunk:
> > > git clone http://llvm.org/git/llvm.git
> > > and
<SNIP>
> > > or: perf record [<options>] -- <command> [<options>]
> > > -e, --event <event> event selector. use 'perf list' to list
> > > available events
> > > [root@felicio ~]#
> > > Now to find a hello.c BPF scriptlet...
So, we do not need to provide all this LLVM environment installation
hints when we get to any error, i.e. the one above was just becasuse
"./foo.c" doesn't exist, clang ran successfully, so no need for telling
the user how to install it.
The following error also shouldn't emit those hints:
[root@felicio ~]# perf record -e ./lock_page.bpf.c sleep 1
/root/./lock_page.bpf.c:1:5: error: expected parameter declarator
SEC("lock_page=__lock_page page->flags")
^
/root/./lock_page.bpf.c:1:5: error: expected ')'
/root/./lock_page.bpf.c:1:4: note: to match this '('
SEC("lock_page=__lock_page page->flags")
^
/root/./lock_page.bpf.c:1:1: warning: type specifier missing, defaults to
'int' [-Wimplicit-int]
SEC("lock_page=__lock_page page->flags")
^
/root/./lock_page.bpf.c:1:41: error: expected ';' after top level declarator
SEC("lock_page=__lock_page page->flags")
^
;
/root/./lock_page.bpf.c:2:22: warning: declaration of 'struct pt_regs' will
not be visible outside of this function [-Wvisibility]
int lock_page(struct pt_regs *ctx, int err, unsigned long flags)
^
2 warnings and 3 errors generated.
ERROR: unable to compile ./lock_page.bpf.c
Hint: Check error message shown above.
LLVM 3.7 or newer is required. Which can be found from http://llvm.org
You may want to try git trunk:
git clone http://llvm.org/git/llvm.git
and
git clone http://llvm.org/git/clang.git
Or fetch the latest clang/llvm 3.7 from pre-built llvm packages for
debian/ubuntu:
http://llvm.org/apt
If you are using old version of clang, change 'clang-bpf-cmd-template'
option in [llvm] section of ~/.perfconfig to:
"$CLANG_EXEC $CLANG_OPTIONS $KERNEL_INC_OPTIONS \
-working-directory $WORKING_DIR -c $CLANG_SOURCE \
-emit-llvm -o - | /path/to/llc -march=bpf -filetype=obj -o -"
(Replace /path/to/llc with path to your llc)
Hint: You can also pre-compile it into .o
invalid or unsupported event: './lock_page.bpf.c'
Run 'perf list' for a list of valid events
usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]
-e, --event <event> event selector. use 'perf list' to list available
events
[root@felicio ~]#
And I am interested in that "Hint: You can also pre-compile it into .o", seems
like a useful one, if it was on the screen, i.e. how can I pre-compile this
into a .o, its some random piece of eBPF "scriptlet" I found in one of your
csets, after this cset in your patchkit:
[root@felicio ~]# cat lock_page.bpf.c
SEC("lock_page=__lock_page page->flags")
int lock_page(struct pt_regs *ctx, int err, unsigned long flags)
{
return 1;
}
[root@felicio ~]#
Also it would be nice to tell the user, when compilation fails, where to look
for a eBPF scriptlet primer, i.e. where can I find some documentation on how
to write such scriptlets?
At this point I expect it to build the .c into a .o, then, as the wiring up is
not there, tell the user that all went well, but more infrastructure is needed,
apply the following patches from Wang Nan! 8-)
- Arnaldo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
