Changes from v2:
* rebased to accomodate b816b3db15f68690ee72a4a414624f8e82942b25 ("kbuild: fix CONFIG_CC_CAN_LINK(_STATIC) for cross-compilation with Clang")
* removed unused FORBID_STATIC_LINK config option
* cc-ed Masahiro Yamada <[email protected]> for can-link.sh approve
This is a continuation of [1]. Since I was able to produce a working UML binary
with UML_NET_VECTOR linked with musl with the changes included in the patches
here. I was compiling on Arch Linux, so hopefully all the latest versions of
the compiler, libraries and binutils.
I also tested allyesconfig with both musl and glibc. The compilation succeeds
with both, however both binaries (glibc one being dynamically linked) segfault
on start. This is probably of some incompatible config option/module being
included and not related to musl/glibc.
[1]: https://patchwork.ozlabs.org/project/linux-um/patch/[email protected]/
Ignat Korchagin (3):
um/kconfig: introduce CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS
um: some fixes to build UML with musl
um: allow static linking for non-glibc implementations
arch/um/Kconfig | 5 +----
arch/um/drivers/Kconfig | 3 ---
arch/um/drivers/daemon_user.c | 1 +
arch/um/drivers/pcap_user.c | 12 ++++++------
arch/um/drivers/slip_user.c | 2 +-
arch/um/drivers/vector_user.c | 4 +---
arch/um/os-Linux/util.c | 2 +-
arch/x86/um/user-offsets.c | 2 +-
init/Kconfig | 6 ++++++
scripts/cc-can-link.sh | 5 +++--
10 files changed, 21 insertions(+), 21 deletions(-)
--
2.20.1
For statically linked UML build it is important to take into account the
standard C-library implementation. Some implementations, notably glibc have
caveats: even when linked statically, the final program might require some
runtime dependencies, if certain functions are used within the code.
Consider the following program:
int main(void)
{
getpwent();
return 0;
}
Compiling this program and linking statically with glibc produces the following
warning from the linker:
/usr/sbin/ld: /tmp/ccuthw1o.o: in function `main':
test.c:(.text+0x5): warning: Using 'getpwent' in statically linked
applications requires at runtime the shared libraries from the glibc version
used for linking
We will use the flag to detect such C-library implementation build time and
possibly disable static linking for UML to avoid producing a binary with
unexpected behaviour and dependencies.
Signed-off-by: Ignat Korchagin <[email protected]>
Reviewed-by: Brendan Higgins <[email protected]>
Tested-by: Brendan Higgins <[email protected]>
---
init/Kconfig | 6 ++++++
scripts/cc-can-link.sh | 5 +++--
2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index 0498af567f70..0a1ec56c9f33 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -57,6 +57,12 @@ config CC_CAN_LINK_STATIC
default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static) if 64BIT
default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static)
+config CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS
+ bool
+ depends on UML && CC_CAN_LINK_STATIC
+ default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m64-flag) -static -Xlinker --fatal-warnings) if 64BIT
+ default $(success,$(srctree)/scripts/cc-can-link.sh $(CC) $(CLANG_FLAGS) $(m32-flag) -static -Xlinker --fatal-warnings)
+
config CC_HAS_ASM_GOTO
def_bool $(success,$(srctree)/scripts/gcc-goto.sh $(CC))
diff --git a/scripts/cc-can-link.sh b/scripts/cc-can-link.sh
index 6efcead31989..e5011a46103e 100755
--- a/scripts/cc-can-link.sh
+++ b/scripts/cc-can-link.sh
@@ -2,10 +2,11 @@
# SPDX-License-Identifier: GPL-2.0
cat << "END" | $@ -x c - -o /dev/null >/dev/null 2>&1
-#include <stdio.h>
+#include <sys/types.h>
+#include <pwd.h>
int main(void)
{
- printf("");
+ getpwent();
return 0;
}
END
--
2.20.1
musl toolchain and headers are a bit more strict. These fixes enable building
UML with musl as well as seem not to break on glibc.
Signed-off-by: Ignat Korchagin <[email protected]>
Tested-by: Brendan Higgins <[email protected]>
---
arch/um/drivers/daemon_user.c | 1 +
arch/um/drivers/pcap_user.c | 12 ++++++------
arch/um/drivers/slip_user.c | 2 +-
arch/um/drivers/vector_user.c | 4 +---
arch/um/os-Linux/util.c | 2 +-
arch/x86/um/user-offsets.c | 2 +-
6 files changed, 11 insertions(+), 12 deletions(-)
diff --git a/arch/um/drivers/daemon_user.c b/arch/um/drivers/daemon_user.c
index 3695821d06a2..785baedc3555 100644
--- a/arch/um/drivers/daemon_user.c
+++ b/arch/um/drivers/daemon_user.c
@@ -7,6 +7,7 @@
*/
#include <stdint.h>
+#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <sys/types.h>
diff --git a/arch/um/drivers/pcap_user.c b/arch/um/drivers/pcap_user.c
index bbd20638788a..52ddda3e3b10 100644
--- a/arch/um/drivers/pcap_user.c
+++ b/arch/um/drivers/pcap_user.c
@@ -32,7 +32,7 @@ static int pcap_user_init(void *data, void *dev)
return 0;
}
-static int pcap_open(void *data)
+static int pcap_user_open(void *data)
{
struct pcap_data *pri = data;
__u32 netmask;
@@ -44,14 +44,14 @@ static int pcap_open(void *data)
if (pri->filter != NULL) {
err = dev_netmask(pri->dev, &netmask);
if (err < 0) {
- printk(UM_KERN_ERR "pcap_open : dev_netmask failed\n");
+ printk(UM_KERN_ERR "pcap_user_open : dev_netmask failed\n");
return -EIO;
}
pri->compiled = uml_kmalloc(sizeof(struct bpf_program),
UM_GFP_KERNEL);
if (pri->compiled == NULL) {
- printk(UM_KERN_ERR "pcap_open : kmalloc failed\n");
+ printk(UM_KERN_ERR "pcap_user_open : kmalloc failed\n");
return -ENOMEM;
}
@@ -59,14 +59,14 @@ static int pcap_open(void *data)
(struct bpf_program *) pri->compiled,
pri->filter, pri->optimize, netmask);
if (err < 0) {
- printk(UM_KERN_ERR "pcap_open : pcap_compile failed - "
+ printk(UM_KERN_ERR "pcap_user_open : pcap_compile failed - "
"'%s'\n", pcap_geterr(pri->pcap));
goto out;
}
err = pcap_setfilter(pri->pcap, pri->compiled);
if (err < 0) {
- printk(UM_KERN_ERR "pcap_open : pcap_setfilter "
+ printk(UM_KERN_ERR "pcap_user_open : pcap_setfilter "
"failed - '%s'\n", pcap_geterr(pri->pcap));
goto out;
}
@@ -127,7 +127,7 @@ int pcap_user_read(int fd, void *buffer, int len, struct pcap_data *pri)
const struct net_user_info pcap_user_info = {
.init = pcap_user_init,
- .open = pcap_open,
+ .open = pcap_user_open,
.close = NULL,
.remove = pcap_remove,
.add_address = NULL,
diff --git a/arch/um/drivers/slip_user.c b/arch/um/drivers/slip_user.c
index 8016d32b6809..482a19c5105c 100644
--- a/arch/um/drivers/slip_user.c
+++ b/arch/um/drivers/slip_user.c
@@ -9,7 +9,7 @@
#include <errno.h>
#include <fcntl.h>
#include <string.h>
-#include <sys/termios.h>
+#include <termios.h>
#include <sys/wait.h>
#include <net_user.h>
#include <os.h>
diff --git a/arch/um/drivers/vector_user.c b/arch/um/drivers/vector_user.c
index c4a0f26b2824..45d4164ad355 100644
--- a/arch/um/drivers/vector_user.c
+++ b/arch/um/drivers/vector_user.c
@@ -18,9 +18,7 @@
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/un.h>
-#include <net/ethernet.h>
#include <netinet/ip.h>
-#include <netinet/ether.h>
#include <linux/if_ether.h>
#include <linux/if_packet.h>
#include <sys/wait.h>
@@ -332,7 +330,7 @@ static struct vector_fds *user_init_unix_fds(struct arglist *ifspec, int id)
}
switch (id) {
case ID_BESS:
- if (connect(fd, remote_addr, sizeof(struct sockaddr_un)) < 0) {
+ if (connect(fd, (const struct sockaddr *) remote_addr, sizeof(struct sockaddr_un)) < 0) {
printk(UM_KERN_ERR "bess open:cannot connect to %s %i", remote_addr->sun_path, -errno);
goto unix_cleanup;
}
diff --git a/arch/um/os-Linux/util.c b/arch/um/os-Linux/util.c
index ecf2f390fad2..07327425d06e 100644
--- a/arch/um/os-Linux/util.c
+++ b/arch/um/os-Linux/util.c
@@ -10,7 +10,7 @@
#include <signal.h>
#include <string.h>
#include <termios.h>
-#include <wait.h>
+#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/utsname.h>
#include <init.h>
diff --git a/arch/x86/um/user-offsets.c b/arch/x86/um/user-offsets.c
index c51dd8363d25..bae61554abcc 100644
--- a/arch/x86/um/user-offsets.c
+++ b/arch/x86/um/user-offsets.c
@@ -2,7 +2,7 @@
#include <stdio.h>
#include <stddef.h>
#include <signal.h>
-#include <sys/poll.h>
+#include <poll.h>
#include <sys/mman.h>
#include <sys/user.h>
#define __FRAME_OFFSETS
--
2.20.1
It is possible to produce a statically linked UML binary with UML_NET_VECTOR,
UML_NET_VDE and UML_NET_PCAP options enabled using alternative libc
implementations, which do not rely on NSS, such as musl.
Allow static linking in this case.
Signed-off-by: Ignat Korchagin <[email protected]>
Reviewed-by: Brendan Higgins <[email protected]>
Tested-by: Brendan Higgins <[email protected]>
---
arch/um/Kconfig | 5 +----
arch/um/drivers/Kconfig | 3 ---
2 files changed, 1 insertion(+), 7 deletions(-)
diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 9318dc6d1a0c..beb98b3b9f75 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -62,12 +62,9 @@ config NR_CPUS
source "arch/$(HEADER_ARCH)/um/Kconfig"
-config FORBID_STATIC_LINK
- bool
-
config STATIC_LINK
bool "Force a static link"
- depends on !FORBID_STATIC_LINK
+ depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || (!UML_NET_VECTOR && !UML_NET_VDE && !UML_NET_PCAP)
help
This option gives you the ability to force a static link of UML.
Normally, UML is linked as a shared binary. This is inconvenient for
diff --git a/arch/um/drivers/Kconfig b/arch/um/drivers/Kconfig
index 9160ead56e33..72d417055782 100644
--- a/arch/um/drivers/Kconfig
+++ b/arch/um/drivers/Kconfig
@@ -234,7 +234,6 @@ config UML_NET_DAEMON
config UML_NET_VECTOR
bool "Vector I/O high performance network devices"
depends on UML_NET
- select FORBID_STATIC_LINK
help
This User-Mode Linux network driver uses multi-message send
and receive functions. The host running the UML guest must have
@@ -246,7 +245,6 @@ config UML_NET_VECTOR
config UML_NET_VDE
bool "VDE transport (obsolete)"
depends on UML_NET
- select FORBID_STATIC_LINK
help
This User-Mode Linux network transport allows one or more running
UMLs on a single host to communicate with each other and also
@@ -294,7 +292,6 @@ config UML_NET_MCAST
config UML_NET_PCAP
bool "pcap transport (obsolete)"
depends on UML_NET
- select FORBID_STATIC_LINK
help
The pcap transport makes a pcap packet stream on the host look
like an ethernet device inside UML. This is useful for making
--
2.20.1
On Wed, 2020-07-15 at 21:11 +0100, Ignat Korchagin wrote:
> It is possible to produce a statically linked UML binary with UML_NET_VECTOR,
> UML_NET_VDE and UML_NET_PCAP options enabled using alternative libc
> implementations, which do not rely on NSS, such as musl.
>
> Allow static linking in this case.
>
> Signed-off-by: Ignat Korchagin <[email protected]>
> Reviewed-by: Brendan Higgins <[email protected]>
> Tested-by: Brendan Higgins <[email protected]>
> ---
> arch/um/Kconfig | 5 +----
> arch/um/drivers/Kconfig | 3 ---
> 2 files changed, 1 insertion(+), 7 deletions(-)
>
> diff --git a/arch/um/Kconfig b/arch/um/Kconfig
> index 9318dc6d1a0c..beb98b3b9f75 100644
> --- a/arch/um/Kconfig
> +++ b/arch/um/Kconfig
> @@ -62,12 +62,9 @@ config NR_CPUS
>
> source "arch/$(HEADER_ARCH)/um/Kconfig"
>
> -config FORBID_STATIC_LINK
> - bool
> -
> config STATIC_LINK
> bool "Force a static link"
> - depends on !FORBID_STATIC_LINK
> + depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || (!UML_NET_VECTOR && !UML_NET_VDE && !UML_NET_PCAP)
Come to think of it, in a way "FORBID_STATIC_LINK" was nicer because
there didn't need to be a single list of "what has dynamic dependencies"
like here the list of UML_NET_VECTOR, UML_NET_VDE, UML_NET_PCAP.
Maybe it could be
config MAY_HAVE_NON_STATIC_RUNTIME_DEPS
bool
config STATIC_LINK
...
depends on !MAY_HAVE_NON_STATIC_RUNTIME_DEPS || CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS
and then UML_NET_VECTOR et al can
select MAY_HAVE_NON_STATIC_RUNTIME_DEPS
so that the knowledge is still distributed to the corresponding options?
johannes
On Thu, Jul 16, 2020 at 10:10 AM Johannes Berg
<[email protected]> wrote:
>
> On Wed, 2020-07-15 at 21:11 +0100, Ignat Korchagin wrote:
> > It is possible to produce a statically linked UML binary with UML_NET_VECTOR,
> > UML_NET_VDE and UML_NET_PCAP options enabled using alternative libc
> > implementations, which do not rely on NSS, such as musl.
> >
> > Allow static linking in this case.
> >
> > Signed-off-by: Ignat Korchagin <[email protected]>
> > Reviewed-by: Brendan Higgins <[email protected]>
> > Tested-by: Brendan Higgins <[email protected]>
> > ---
> > arch/um/Kconfig | 5 +----
> > arch/um/drivers/Kconfig | 3 ---
> > 2 files changed, 1 insertion(+), 7 deletions(-)
> >
> > diff --git a/arch/um/Kconfig b/arch/um/Kconfig
> > index 9318dc6d1a0c..beb98b3b9f75 100644
> > --- a/arch/um/Kconfig
> > +++ b/arch/um/Kconfig
> > @@ -62,12 +62,9 @@ config NR_CPUS
> >
> > source "arch/$(HEADER_ARCH)/um/Kconfig"
> >
> > -config FORBID_STATIC_LINK
> > - bool
> > -
> > config STATIC_LINK
> > bool "Force a static link"
> > - depends on !FORBID_STATIC_LINK
> > + depends on CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS || (!UML_NET_VECTOR && !UML_NET_VDE && !UML_NET_PCAP)
>
> Come to think of it, in a way "FORBID_STATIC_LINK" was nicer because
> there didn't need to be a single list of "what has dynamic dependencies"
> like here the list of UML_NET_VECTOR, UML_NET_VDE, UML_NET_PCAP.
>
> Maybe it could be
>
> config MAY_HAVE_NON_STATIC_RUNTIME_DEPS
> bool
>
> config STATIC_LINK
> ...
> depends on !MAY_HAVE_NON_STATIC_RUNTIME_DEPS || CC_CAN_LINK_STATIC_NO_RUNTIME_DEPS
>
>
> and then UML_NET_VECTOR et al can
>
> select MAY_HAVE_NON_STATIC_RUNTIME_DEPS
>
> so that the knowledge is still distributed to the corresponding options?
Yes, makes sense. I've shortened it to MAY_HAVE_RUNTIME_DEPS and
reposted the series.
> johannes
>