Re: Fixed modular kernel path and different kernels

[Paul Goyette <paul%whooppee.com@localhost>]

On Wed, 18 Jan 2017, Paul Goyette wrote:

> > One obvious and trivial way to allow for testing like this is to have
> > boot -a also ask for an override of the module path.
>
> This should not be too difficult, although it would (continue to) have the 
> restriction that modules "pushed" from the boot loader (those which are 
> loaded via /boot.conf as well as those automatically pushed for non-ffs 
> boot-device file systems) would continue to be loaded from the boot device.
>
> > Once that is there, also provide the override via userconf or
> > /boot.cfg.
>
> Would this really be necessary?  Do we have the ability to set the root file 
> system via userconf or /boot.cfg?  (Neither the boot.cfg(5) nor userconf(4) 
> man pages hint that this is available?)
>
>
> With a goal of improving the useability of kernel modularity, I'd be happy to 
> implement this capability (WRT boot -a), if there's some sort of consensus.

I've gone ahead and implemented this - see attached patches.

Code review appreciated, as well as comments on whether or not this 
should be committed.




+------------------+--------------------------+------------------------+
| Paul Goyette     | PGP Key fingerprint:     | E-mail addresses:      |
| (Retired)        | FA29 0E3B 35AF E8AE 6651 | paul at whooppee.com   |
| Kernel Developer | 0786 F758 55DE 53BA 7731 | pgoyette at netbsd.org |
+------------------+--------------------------+------------------------+

Index: share/man/man8/boot.8
===================================================================
RCS file: /cvsroot/src/share/man/man8/boot.8,v
retrieving revision 1.15
diff -u -p -r1.15 boot.8
--- share/man/man8/boot.8	16 Aug 2014 11:39:47 -0000	1.15
+++ share/man/man8/boot.8	18 Jan 2017 05:46:19 -0000
@@ -141,6 +141,12 @@ flag in
 This causes the kernel to prompt for the root file system device,
 the system crash dump device, and the path to
 .Xr init 8 .
+For modular kernels (see
+.Cd MODULAR
+in
+.Xr options 4 ) ,
+the kernel will also prompt for the path used for
+loading kernel modules.
 .It Fl b
 Sets the
 .Sy RB_HALT
Index: sys/sys/module.h
===================================================================
RCS file: /cvsroot/src/sys/sys/module.h,v
retrieving revision 1.41
diff -u -p -r1.41 module.h
--- sys/sys/module.h	16 Nov 2016 10:42:14 -0000	1.41
+++ sys/sys/module.h	18 Jan 2017 05:46:19 -0000
@@ -170,7 +170,7 @@ extern struct modlist	module_list;
 extern struct modlist	module_builtins;
 extern u_int		module_gen;
 
-void	module_init(void);
+void	module_init(int);
 void	module_start_unload_thread(void);
 void	module_builtin_require_force(void);
 void	module_init_md(void);
Index: sys/kern/init_main.c
===================================================================
RCS file: /cvsroot/src/sys/kern/init_main.c,v
retrieving revision 1.490
diff -u -p -r1.490 init_main.c
--- sys/kern/init_main.c	16 Jan 2017 09:28:40 -0000	1.490
+++ sys/kern/init_main.c	18 Jan 2017 05:46:19 -0000
@@ -337,7 +337,7 @@ main(void)
 	bpf_setops();
 
 	/* Start module system. */
-	module_init();
+	module_init(boothowto & RB_ASKNAME);
 
 	/*
 	 * Initialize the kernel authorization subsystem and start the
Index: sys/kern/kern_module.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kern_module.c,v
retrieving revision 1.119
diff -u -p -r1.119 kern_module.c
--- sys/kern/kern_module.c	27 Dec 2016 09:34:44 -0000	1.119
+++ sys/kern/kern_module.c	18 Jan 2017 05:46:19 -0000
@@ -55,6 +55,8 @@ __KERNEL_RCSID(0, "$NetBSD: kern_module.
 #include <sys/sysctl.h>
 #include <sys/lock.h>
 
+#include <dev/cons.h>	/* for cngetsn() (prompting for module path) */
+
 #include <uvm/uvm_extern.h>
 
 struct vm_map *module_map;
@@ -337,7 +339,7 @@ module_builtin_remove(modinfo_t *mi, boo
  *	Initialize the module subsystem.
  */
 void
-module_init(void)
+module_init(int askpath)
 {
 	__link_set_decl(modules, modinfo_t);
 	extern struct vm_map *module_map;
@@ -365,6 +367,22 @@ module_init(void)
 	    __NetBSD_Version__ / 1000000 % 100);
 #endif
 
+#ifdef _RUMPKERNEL	/* rump kernel does not provide console read/get */
+	KASSERT(askpath == 0);
+#else
+#ifdef MODULAR
+	if (askpath != 0) {
+		int len;
+		char module_path[MODULE_BASE_SIZE];
+
+		printf("module path (default %s): ", module_base);
+		len = cngetsn(module_path, sizeof(module_path)-1);
+		if (len != 0)
+			strlcpy(module_base, module_path, sizeof(module_base));
+	}
+#endif /* defined(MODULAR) */
+#endif
+
 	module_listener = kauth_listen_scope(KAUTH_SCOPE_SYSTEM,
 	    module_listener_cb, NULL);
 
Index: sys/rump/librump/rumpkern/rump.c
===================================================================
RCS file: /cvsroot/src/sys/rump/librump/rumpkern/rump.c,v
retrieving revision 1.329
diff -u -p -r1.329 rump.c
--- sys/rump/librump/rumpkern/rump.c	8 Mar 2016 14:30:48 -0000	1.329
+++ sys/rump/librump/rumpkern/rump.c	18 Jan 2017 05:46:19 -0000
@@ -400,7 +400,7 @@ rump_init(void)
 	kqueue_init();
 	iostat_init();
 	fd_sys_init();
-	module_init();
+	module_init(0);
 	devsw_init();
 	pipe_init();
 	resource_init();