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From:   Ignat Korchagin <ignat@cloudflare.com>
To:     jdike@addtoit.com, richard@nod.at, anton.ivanov@cambridgegreys.com,
        brendanhiggins@google.com, masahiroy@kernel.org,
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Cc:     Ignat Korchagin <ignat@cloudflare.com>, kernel-team@cloudflare.com
Subject: [PATCH v3 3/3] um: allow static linking for non-glibc implementations
Date:   Wed, 15 Jul 2020 21:11:59 +0100
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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 <ignat@cloudflare.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
---
 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