Commit e8330d9b authored by Rusty Russell's avatar Rusty Russell
Browse files

lguest: support emerg_wr in console device in example launcher. 



This is a magic register which causes a character to be outputted: it can
be used even before the device is configured.

Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
parent b3e28b65

tools/lguest/lguest.c

+14 −3
Original line number Diff line number Diff line
@@ -71,7 +71,7 @@ typedef uint8_t u8; 
#include "../../include/uapi/linux/virtio_config.h"

#include "../../include/uapi/linux/virtio_net.h"

#include "../../include/uapi/linux/virtio_blk.h"

#include <linux/virtio_console.h>

#include "../../include/uapi/linux/virtio_console.h"

#include "../../include/uapi/linux/virtio_rng.h"

#include <linux/virtio_ring.h>

#include "../../include/uapi/linux/virtio_pci.h"
@@ -1687,6 +1687,15 @@ static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask) 
		goto write_through16;

	case offsetof(struct virtio_pci_mmio, isr):

		errx(1, "%s: Unexpected write to isr", d->name);

	/* Weird corner case: write to emerg_wr of console */

	case sizeof(struct virtio_pci_mmio)

		+ offsetof(struct virtio_console_config, emerg_wr):

		if (strcmp(d->name, "console") == 0) {

			char c = val;

			write(STDOUT_FILENO, &c, 1);

			goto write_through32;

		}

		/* Fall through... */

	default:

		errx(1, "%s: Unexpected write to offset %u", d->name, off);

	}
@@ -2048,6 +2057,7 @@ static struct device *new_pci_device(const char *name, u16 type, 
static void setup_console(void)

{

	struct device *dev;

	struct virtio_console_config conf;



	/* If we can save the initial standard input settings... */

	if (tcgetattr(STDIN_FILENO, &orig_term) == 0) {
@@ -2075,8 +2085,9 @@ static void setup_console(void) 
	add_pci_virtqueue(dev, console_input);

	add_pci_virtqueue(dev, console_output);



	/* There's no configuration area for this device. */

	no_device_config(dev);

	/* We need a configuration area for the emerg_wr early writes. */

	add_pci_feature(dev, VIRTIO_CONSOLE_F_EMERG_WRITE);

	set_device_config(dev, &conf, sizeof(conf));



	verbose("device %u: console\n", devices.device_num);

}