Add the address of IDT in the configuration ROM. (i386/amd64 only)

A change to dconschat(8) will follow so that it can bomb
this address over FireWire to reset a wedged system.

Though this method is just a hack and far from perfection,
it should be useful if you don't want to go machine room
just to reset or to power-cycle a machine without
remote-managed power supply.  And much better than doing:
# fwcontrol -m target-eui64
# dd if=/dev/zero of=/dev/fwmem0.2 bs=1m

2 files changed, 27 insertions, 0 deletions

diff --git a/sys/dev/dcons/dcons.h b/sys/dev/dcons/dcons.h
index daf9cb4..49ef869 100644
--- a/sys/dev/dcons/dcons.h
+++ b/sys/dev/dcons/dcons.h
@@ -65,6 +65,8 @@ struct dcons_buf {
 #define DCONS_CSR_VAL_VER	0x64636f /* "dco" */
 #define DCONS_CSR_KEY_HI	0x3a
 #define DCONS_CSR_KEY_LO	0x3b
+#define DCONS_CSR_KEY_RESET_HI	0x3c
+#define DCONS_CSR_KEY_RESET_LO	0x3d
 
 #define	DCONS_HEADER_SIZE sizeof(struct dcons_buf)
 #define DCONS_MAKE_PTR(x)	htonl(((x)->gen << DCONS_GEN_SHIFT) | (x)->pos)
@@ -88,6 +90,7 @@ struct dcons_ch {
 #define STATE0		0
 #define STATE1		1
 #define STATE2		2
+#define STATE3		3
 
 #if defined(_KERNEL) || defined(_BOOT)
 struct dcons_softc {
diff --git a/sys/dev/dcons/dcons_crom.c b/sys/dev/dcons/dcons_crom.c
index 290c80a..290bb1e 100644
--- a/sys/dev/dcons/dcons_crom.c
+++ b/sys/dev/dcons/dcons_crom.c
@@ -62,6 +62,14 @@
 
 #include <sys/cons.h>
 
+#define EXPOSE_IDT_ADDR 1
+
+#if (defined(__i386__) || defined(__amd64__)) && defined(EXPOSE_IDT_ADDR)
+#include <vm/vm.h>
+#include <vm/vm_param.h>
+#include <vm/pmap.h>
+#include <machine/segments.h> /* for idt */
+#endif
 static bus_addr_t dcons_paddr;
 
 #if __FreeBSD_version >= 500000
@@ -108,6 +116,19 @@ dcons_crom_probe(device_t dev)
 }
 
 #ifndef NEED_NEW_DRIVER
+#if (defined(__i386__) || defined(__amd64__)) && defined(EXPOSE_IDT_ADDR)
+static void
+dcons_crom_expose_idt(struct dcons_crom_softc *sc)
+{
+	static off_t idt_paddr;
+
+	/* XXX */
+	idt_paddr = (char *)idt - (char *)KERNBASE;
+
+	crom_add_entry(&sc->unit, DCONS_CSR_KEY_RESET_HI, ADDR_HI(idt_paddr));
+	crom_add_entry(&sc->unit, DCONS_CSR_KEY_RESET_LO, ADDR_LO(idt_paddr));
+}
+#endif
 static void
 dcons_crom_post_busreset(void *arg)
 {
@@ -128,6 +149,9 @@ dcons_crom_post_busreset(void *arg)
 	crom_add_simple_text(src, &sc->unit, &sc->ver, "dcons");
 	crom_add_entry(&sc->unit, DCONS_CSR_KEY_HI, ADDR_HI(dcons_paddr));
 	crom_add_entry(&sc->unit, DCONS_CSR_KEY_LO, ADDR_LO(dcons_paddr));
+#if (defined(__i386__) || defined(__amd64__)) && defined(EXPOSE_IDT_ADDR)
+	dcons_crom_expose_idt(sc);
+#endif
 }
 #endif