linux-kernel - [PATCH v2] uml: make CONFIG_STATIC

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Message-Id: <20200123235914.223178-1-brendanhiggins@google.com>
Date:   Thu, 23 Jan 2020 15:59:14 -0800
From:   Brendan Higgins <brendanhiggins@...gle.com>
To:     jdike@...toit.com, richard@....at, anton.ivanov@...bridgegreys.com,
        geert@...ux-m68k.org, james_mcmechan@...mail.com
Cc:     linux-um@...ts.infradead.org, linux-kernel@...r.kernel.org,
        davidgow@...gle.com, Brendan Higgins <brendanhiggins@...gle.com>
Subject: [PATCH v2] uml: make CONFIG_STATIC_LINK actually static

Currently, CONFIG_STATIC_LINK can be enabled with options which cannot
be statically linked, namely UML_NET_VECTOR, UML_NET_VDE, and
UML_NET_PCAP; this is because glibc tries to load NSS which does not
support being statically linked. So make CONFIG_STATIC_LINK depend on
!UML_NET_VECTOR && !UML_NET_VDE && !UML_NET_PCAP.

Link: https://lore.kernel.org/lkml/f658f317-be54-ed75-8296-c373c2dcc697@cambridgegreys.com/#t
Signed-off-by: Brendan Higgins <brendanhiggins@...gle.com>
---
Changes since last revision:

Incorporated Geert Uytterhoeven's suggestion of using a separate
FORBID_STATIC_LINK config option that each driver incompatible with
static linking selects.
---
 arch/um/Kconfig         | 7 +++++++
 arch/um/drivers/Kconfig | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 0917f8443c285..27a51e7dd59c6 100644
--- a/arch/um/Kconfig
+++ b/arch/um/Kconfig
@@ -62,8 +62,12 @@ config NR_CPUS
 
 source "arch/$(HEADER_ARCH)/um/Kconfig"
 
+config FORBID_STATIC_LINK
+	def_bool n
+
 config STATIC_LINK
 	bool "Force a static link"
+	depends on !FORBID_STATIC_LINK
 	default n
 	help
 	  This option gives you the ability to force a static link of UML.
@@ -73,6 +77,9 @@ config STATIC_LINK
 	  Additionally, this option enables using higher memory spaces (up to
 	  2.75G) for UML.
 
+	  NOTE: This option is incompatible with some networking features which
+	  depend on features that require being dynamically loaded (like NSS).
+
 config LD_SCRIPT_STATIC
 	bool
 	default y
diff --git a/arch/um/drivers/Kconfig b/arch/um/drivers/Kconfig
index 72d4170557820..9160ead56e33c 100644
--- a/arch/um/drivers/Kconfig
+++ b/arch/um/drivers/Kconfig
@@ -234,6 +234,7 @@ 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
@@ -245,6 +246,7 @@ 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
@@ -292,6 +294,7 @@ 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
-- 
2.25.0.341.g760bfbb309-goog