1 | // SPDX-License-Identifier: GPL-2.0+ |
2 | /* |
3 | * xen console driver interface to hvc_console.c |
4 | * |
5 | * (c) 2007 Gerd Hoffmann <kraxel@suse.de> |
6 | */ |
7 | |
8 | #include <linux/console.h> |
9 | #include <linux/delay.h> |
10 | #include <linux/err.h> |
11 | #include <linux/irq.h> |
12 | #include <linux/init.h> |
13 | #include <linux/types.h> |
14 | #include <linux/list.h> |
15 | #include <linux/serial_core.h> |
16 | |
17 | #include <asm/io.h> |
18 | #include <asm/xen/hypervisor.h> |
19 | |
20 | #include <xen/xen.h> |
21 | #include <xen/interface/xen.h> |
22 | #include <xen/hvm.h> |
23 | #include <xen/grant_table.h> |
24 | #include <xen/page.h> |
25 | #include <xen/events.h> |
26 | #include <xen/interface/io/console.h> |
27 | #include <xen/interface/sched.h> |
28 | #include <xen/hvc-console.h> |
29 | #include <xen/xenbus.h> |
30 | |
31 | #include "hvc_console.h" |
32 | |
33 | #define HVC_COOKIE 0x58656e /* "Xen" in hex */ |
34 | |
35 | struct xencons_info { |
36 | struct list_head list; |
37 | struct xenbus_device *xbdev; |
38 | struct xencons_interface *intf; |
39 | unsigned int evtchn; |
40 | struct hvc_struct *hvc; |
41 | int irq; |
42 | int vtermno; |
43 | grant_ref_t gntref; |
44 | }; |
45 | |
46 | static LIST_HEAD(xenconsoles); |
47 | static DEFINE_SPINLOCK(xencons_lock); |
48 | |
49 | /* ------------------------------------------------------------------ */ |
50 | |
51 | static struct xencons_info *vtermno_to_xencons(int vtermno) |
52 | { |
53 | struct xencons_info *entry, *n, *ret = NULL; |
54 | |
55 | if (list_empty(&xenconsoles)) |
56 | return NULL; |
57 | |
58 | list_for_each_entry_safe(entry, n, &xenconsoles, list) { |
59 | if (entry->vtermno == vtermno) { |
60 | ret = entry; |
61 | break; |
62 | } |
63 | } |
64 | |
65 | return ret; |
66 | } |
67 | |
68 | static inline int xenbus_devid_to_vtermno(int devid) |
69 | { |
70 | return devid + HVC_COOKIE; |
71 | } |
72 | |
73 | static inline void notify_daemon(struct xencons_info *cons) |
74 | { |
75 | /* Use evtchn: this is called early, before irq is set up. */ |
76 | notify_remote_via_evtchn(cons->evtchn); |
77 | } |
78 | |
79 | static int __write_console(struct xencons_info *xencons, |
80 | const char *data, int len) |
81 | { |
82 | XENCONS_RING_IDX cons, prod; |
83 | struct xencons_interface *intf = xencons->intf; |
84 | int sent = 0; |
85 | |
86 | cons = intf->out_cons; |
87 | prod = intf->out_prod; |
88 | mb(); /* update queue values before going on */ |
89 | BUG_ON((prod - cons) > sizeof(intf->out)); |
90 | |
91 | while ((sent < len) && ((prod - cons) < sizeof(intf->out))) |
92 | intf->out[MASK_XENCONS_IDX(prod++, intf->out)] = data[sent++]; |
93 | |
94 | wmb(); /* write ring before updating pointer */ |
95 | intf->out_prod = prod; |
96 | |
97 | if (sent) |
98 | notify_daemon(xencons); |
99 | return sent; |
100 | } |
101 | |
102 | static int domU_write_console(uint32_t vtermno, const char *data, int len) |
103 | { |
104 | int ret = len; |
105 | struct xencons_info *cons = vtermno_to_xencons(vtermno); |
106 | if (cons == NULL) |
107 | return -EINVAL; |
108 | |
109 | /* |
110 | * Make sure the whole buffer is emitted, polling if |
111 | * necessary. We don't ever want to rely on the hvc daemon |
112 | * because the most interesting console output is when the |
113 | * kernel is crippled. |
114 | */ |
115 | while (len) { |
116 | int sent = __write_console(cons, data, len); |
117 | |
118 | data += sent; |
119 | len -= sent; |
120 | |
121 | if (unlikely(len)) |
122 | HYPERVISOR_sched_op(SCHEDOP_yield, NULL); |
123 | } |
124 | |
125 | return ret; |
126 | } |
127 | |
128 | static int domU_read_console(uint32_t vtermno, char *buf, int len) |
129 | { |
130 | struct xencons_interface *intf; |
131 | XENCONS_RING_IDX cons, prod; |
132 | int recv = 0; |
133 | struct xencons_info *xencons = vtermno_to_xencons(vtermno); |
134 | if (xencons == NULL) |
135 | return -EINVAL; |
136 | intf = xencons->intf; |
137 | |
138 | cons = intf->in_cons; |
139 | prod = intf->in_prod; |
140 | mb(); /* get pointers before reading ring */ |
141 | BUG_ON((prod - cons) > sizeof(intf->in)); |
142 | |
143 | while (cons != prod && recv < len) |
144 | buf[recv++] = intf->in[MASK_XENCONS_IDX(cons++, intf->in)]; |
145 | |
146 | mb(); /* read ring before consuming */ |
147 | intf->in_cons = cons; |
148 | |
149 | notify_daemon(xencons); |
150 | return recv; |
151 | } |
152 | |
153 | static const struct hv_ops domU_hvc_ops = { |
154 | .get_chars = domU_read_console, |
155 | .put_chars = domU_write_console, |
156 | .notifier_add = notifier_add_irq, |
157 | .notifier_del = notifier_del_irq, |
158 | .notifier_hangup = notifier_hangup_irq, |
159 | }; |
160 | |
161 | static int dom0_read_console(uint32_t vtermno, char *buf, int len) |
162 | { |
163 | return HYPERVISOR_console_io(CONSOLEIO_read, len, buf); |
164 | } |
165 | |
166 | /* |
167 | * Either for a dom0 to write to the system console, or a domU with a |
168 | * debug version of Xen |
169 | */ |
170 | static int dom0_write_console(uint32_t vtermno, const char *str, int len) |
171 | { |
172 | int rc = HYPERVISOR_console_io(CONSOLEIO_write, len, (char *)str); |
173 | if (rc < 0) |
174 | return rc; |
175 | |
176 | return len; |
177 | } |
178 | |
179 | static const struct hv_ops dom0_hvc_ops = { |
180 | .get_chars = dom0_read_console, |
181 | .put_chars = dom0_write_console, |
182 | .notifier_add = notifier_add_irq, |
183 | .notifier_del = notifier_del_irq, |
184 | .notifier_hangup = notifier_hangup_irq, |
185 | }; |
186 | |
187 | static int xen_hvm_console_init(void) |
188 | { |
189 | int r; |
190 | uint64_t v = 0; |
191 | unsigned long gfn; |
192 | struct xencons_info *info; |
193 | |
194 | if (!xen_hvm_domain()) |
195 | return -ENODEV; |
196 | |
197 | info = vtermno_to_xencons(HVC_COOKIE); |
198 | if (!info) { |
199 | info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); |
200 | if (!info) |
201 | return -ENOMEM; |
202 | } else if (info->intf != NULL) { |
203 | /* already configured */ |
204 | return 0; |
205 | } |
206 | /* |
207 | * If the toolstack (or the hypervisor) hasn't set these values, the |
208 | * default value is 0. Even though gfn = 0 and evtchn = 0 are |
209 | * theoretically correct values, in practice they never are and they |
210 | * mean that a legacy toolstack hasn't initialized the pv console correctly. |
211 | */ |
212 | r = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v); |
213 | if (r < 0 || v == 0) |
214 | goto err; |
215 | info->evtchn = v; |
216 | v = 0; |
217 | r = hvm_get_parameter(HVM_PARAM_CONSOLE_PFN, &v); |
218 | if (r < 0 || v == 0) |
219 | goto err; |
220 | gfn = v; |
221 | info->intf = xen_remap(gfn << XEN_PAGE_SHIFT, XEN_PAGE_SIZE); |
222 | if (info->intf == NULL) |
223 | goto err; |
224 | info->vtermno = HVC_COOKIE; |
225 | |
226 | spin_lock(&xencons_lock); |
227 | list_add_tail(&info->list, &xenconsoles); |
228 | spin_unlock(&xencons_lock); |
229 | |
230 | return 0; |
231 | err: |
232 | kfree(info); |
233 | return -ENODEV; |
234 | } |
235 | |
236 | static int xencons_info_pv_init(struct xencons_info *info, int vtermno) |
237 | { |
238 | info->evtchn = xen_start_info->console.domU.evtchn; |
239 | /* GFN == MFN for PV guest */ |
240 | info->intf = gfn_to_virt(xen_start_info->console.domU.mfn); |
241 | info->vtermno = vtermno; |
242 | |
243 | list_add_tail(&info->list, &xenconsoles); |
244 | |
245 | return 0; |
246 | } |
247 | |
248 | static int xen_pv_console_init(void) |
249 | { |
250 | struct xencons_info *info; |
251 | |
252 | if (!xen_pv_domain()) |
253 | return -ENODEV; |
254 | |
255 | if (!xen_start_info->console.domU.evtchn) |
256 | return -ENODEV; |
257 | |
258 | info = vtermno_to_xencons(HVC_COOKIE); |
259 | if (!info) { |
260 | info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); |
261 | if (!info) |
262 | return -ENOMEM; |
263 | } else if (info->intf != NULL) { |
264 | /* already configured */ |
265 | return 0; |
266 | } |
267 | spin_lock(&xencons_lock); |
268 | xencons_info_pv_init(info, HVC_COOKIE); |
269 | spin_unlock(&xencons_lock); |
270 | |
271 | return 0; |
272 | } |
273 | |
274 | static int xen_initial_domain_console_init(void) |
275 | { |
276 | struct xencons_info *info; |
277 | |
278 | if (!xen_initial_domain()) |
279 | return -ENODEV; |
280 | |
281 | info = vtermno_to_xencons(HVC_COOKIE); |
282 | if (!info) { |
283 | info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); |
284 | if (!info) |
285 | return -ENOMEM; |
286 | } |
287 | |
288 | info->irq = bind_virq_to_irq(VIRQ_CONSOLE, 0, false); |
289 | info->vtermno = HVC_COOKIE; |
290 | |
291 | spin_lock(&xencons_lock); |
292 | list_add_tail(&info->list, &xenconsoles); |
293 | spin_unlock(&xencons_lock); |
294 | |
295 | return 0; |
296 | } |
297 | |
298 | static void xen_console_update_evtchn(struct xencons_info *info) |
299 | { |
300 | if (xen_hvm_domain()) { |
301 | uint64_t v = 0; |
302 | int err; |
303 | |
304 | err = hvm_get_parameter(HVM_PARAM_CONSOLE_EVTCHN, &v); |
305 | if (!err && v) |
306 | info->evtchn = v; |
307 | } else |
308 | info->evtchn = xen_start_info->console.domU.evtchn; |
309 | } |
310 | |
311 | void xen_console_resume(void) |
312 | { |
313 | struct xencons_info *info = vtermno_to_xencons(HVC_COOKIE); |
314 | if (info != NULL && info->irq) { |
315 | if (!xen_initial_domain()) |
316 | xen_console_update_evtchn(info); |
317 | rebind_evtchn_irq(info->evtchn, info->irq); |
318 | } |
319 | } |
320 | |
321 | #ifdef CONFIG_HVC_XEN_FRONTEND |
322 | static void xencons_disconnect_backend(struct xencons_info *info) |
323 | { |
324 | if (info->irq > 0) |
325 | unbind_from_irqhandler(info->irq, NULL); |
326 | info->irq = 0; |
327 | if (info->evtchn > 0) |
328 | xenbus_free_evtchn(info->xbdev, info->evtchn); |
329 | info->evtchn = 0; |
330 | if (info->gntref > 0) |
331 | gnttab_free_grant_references(info->gntref); |
332 | info->gntref = 0; |
333 | if (info->hvc != NULL) |
334 | hvc_remove(info->hvc); |
335 | info->hvc = NULL; |
336 | } |
337 | |
338 | static void xencons_free(struct xencons_info *info) |
339 | { |
340 | free_page((unsigned long)info->intf); |
341 | info->intf = NULL; |
342 | info->vtermno = 0; |
343 | kfree(info); |
344 | } |
345 | |
346 | static int xen_console_remove(struct xencons_info *info) |
347 | { |
348 | xencons_disconnect_backend(info); |
349 | spin_lock(&xencons_lock); |
350 | list_del(&info->list); |
351 | spin_unlock(&xencons_lock); |
352 | if (info->xbdev != NULL) |
353 | xencons_free(info); |
354 | else { |
355 | if (xen_hvm_domain()) |
356 | iounmap(info->intf); |
357 | kfree(info); |
358 | } |
359 | return 0; |
360 | } |
361 | |
362 | static int xencons_remove(struct xenbus_device *dev) |
363 | { |
364 | return xen_console_remove(dev_get_drvdata(&dev->dev)); |
365 | } |
366 | |
367 | static int xencons_connect_backend(struct xenbus_device *dev, |
368 | struct xencons_info *info) |
369 | { |
370 | int ret, evtchn, devid, ref, irq; |
371 | struct xenbus_transaction xbt; |
372 | grant_ref_t gref_head; |
373 | |
374 | ret = xenbus_alloc_evtchn(dev, &evtchn); |
375 | if (ret) |
376 | return ret; |
377 | info->evtchn = evtchn; |
378 | irq = bind_evtchn_to_irq(evtchn); |
379 | if (irq < 0) |
380 | return irq; |
381 | info->irq = irq; |
382 | devid = dev->nodename[strlen(dev->nodename) - 1] - '0'; |
383 | info->hvc = hvc_alloc(xenbus_devid_to_vtermno(devid), |
384 | irq, &domU_hvc_ops, 256); |
385 | if (IS_ERR(info->hvc)) |
386 | return PTR_ERR(info->hvc); |
387 | ret = gnttab_alloc_grant_references(1, &gref_head); |
388 | if (ret < 0) |
389 | return ret; |
390 | info->gntref = gref_head; |
391 | ref = gnttab_claim_grant_reference(&gref_head); |
392 | if (ref < 0) |
393 | return ref; |
394 | gnttab_grant_foreign_access_ref(ref, info->xbdev->otherend_id, |
395 | virt_to_gfn(info->intf), 0); |
396 | |
397 | again: |
398 | ret = xenbus_transaction_start(&xbt); |
399 | if (ret) { |
400 | xenbus_dev_fatal(dev, ret, "starting transaction" ); |
401 | return ret; |
402 | } |
403 | ret = xenbus_printf(xbt, dev->nodename, "ring-ref" , "%d" , ref); |
404 | if (ret) |
405 | goto error_xenbus; |
406 | ret = xenbus_printf(xbt, dev->nodename, "port" , "%u" , |
407 | evtchn); |
408 | if (ret) |
409 | goto error_xenbus; |
410 | ret = xenbus_transaction_end(xbt, 0); |
411 | if (ret) { |
412 | if (ret == -EAGAIN) |
413 | goto again; |
414 | xenbus_dev_fatal(dev, ret, "completing transaction" ); |
415 | return ret; |
416 | } |
417 | |
418 | xenbus_switch_state(dev, XenbusStateInitialised); |
419 | return 0; |
420 | |
421 | error_xenbus: |
422 | xenbus_transaction_end(xbt, 1); |
423 | xenbus_dev_fatal(dev, ret, "writing xenstore" ); |
424 | return ret; |
425 | } |
426 | |
427 | static int xencons_probe(struct xenbus_device *dev, |
428 | const struct xenbus_device_id *id) |
429 | { |
430 | int ret, devid; |
431 | struct xencons_info *info; |
432 | |
433 | devid = dev->nodename[strlen(dev->nodename) - 1] - '0'; |
434 | if (devid == 0) |
435 | return -ENODEV; |
436 | |
437 | info = kzalloc(sizeof(struct xencons_info), GFP_KERNEL); |
438 | if (!info) |
439 | return -ENOMEM; |
440 | dev_set_drvdata(&dev->dev, info); |
441 | info->xbdev = dev; |
442 | info->vtermno = xenbus_devid_to_vtermno(devid); |
443 | info->intf = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO); |
444 | if (!info->intf) |
445 | goto error_nomem; |
446 | |
447 | ret = xencons_connect_backend(dev, info); |
448 | if (ret < 0) |
449 | goto error; |
450 | spin_lock(&xencons_lock); |
451 | list_add_tail(&info->list, &xenconsoles); |
452 | spin_unlock(&xencons_lock); |
453 | |
454 | return 0; |
455 | |
456 | error_nomem: |
457 | ret = -ENOMEM; |
458 | xenbus_dev_fatal(dev, ret, "allocating device memory" ); |
459 | error: |
460 | xencons_disconnect_backend(info); |
461 | xencons_free(info); |
462 | return ret; |
463 | } |
464 | |
465 | static int xencons_resume(struct xenbus_device *dev) |
466 | { |
467 | struct xencons_info *info = dev_get_drvdata(&dev->dev); |
468 | |
469 | xencons_disconnect_backend(info); |
470 | memset(info->intf, 0, XEN_PAGE_SIZE); |
471 | return xencons_connect_backend(dev, info); |
472 | } |
473 | |
474 | static void xencons_backend_changed(struct xenbus_device *dev, |
475 | enum xenbus_state backend_state) |
476 | { |
477 | switch (backend_state) { |
478 | case XenbusStateReconfiguring: |
479 | case XenbusStateReconfigured: |
480 | case XenbusStateInitialising: |
481 | case XenbusStateInitialised: |
482 | case XenbusStateUnknown: |
483 | break; |
484 | |
485 | case XenbusStateInitWait: |
486 | break; |
487 | |
488 | case XenbusStateConnected: |
489 | xenbus_switch_state(dev, XenbusStateConnected); |
490 | break; |
491 | |
492 | case XenbusStateClosed: |
493 | if (dev->state == XenbusStateClosed) |
494 | break; |
495 | /* fall through - Missed the backend's CLOSING state. */ |
496 | case XenbusStateClosing: |
497 | xenbus_frontend_closed(dev); |
498 | break; |
499 | } |
500 | } |
501 | |
502 | static const struct xenbus_device_id xencons_ids[] = { |
503 | { "console" }, |
504 | { "" } |
505 | }; |
506 | |
507 | static struct xenbus_driver xencons_driver = { |
508 | .name = "xenconsole" , |
509 | .ids = xencons_ids, |
510 | .probe = xencons_probe, |
511 | .remove = xencons_remove, |
512 | .resume = xencons_resume, |
513 | .otherend_changed = xencons_backend_changed, |
514 | }; |
515 | #endif /* CONFIG_HVC_XEN_FRONTEND */ |
516 | |
517 | static int __init xen_hvc_init(void) |
518 | { |
519 | int r; |
520 | struct xencons_info *info; |
521 | const struct hv_ops *ops; |
522 | |
523 | if (!xen_domain()) |
524 | return -ENODEV; |
525 | |
526 | if (xen_initial_domain()) { |
527 | ops = &dom0_hvc_ops; |
528 | r = xen_initial_domain_console_init(); |
529 | if (r < 0) |
530 | return r; |
531 | info = vtermno_to_xencons(HVC_COOKIE); |
532 | } else { |
533 | ops = &domU_hvc_ops; |
534 | if (xen_hvm_domain()) |
535 | r = xen_hvm_console_init(); |
536 | else |
537 | r = xen_pv_console_init(); |
538 | if (r < 0) |
539 | return r; |
540 | |
541 | info = vtermno_to_xencons(HVC_COOKIE); |
542 | info->irq = bind_evtchn_to_irq(info->evtchn); |
543 | } |
544 | if (info->irq < 0) |
545 | info->irq = 0; /* NO_IRQ */ |
546 | else |
547 | irq_set_noprobe(info->irq); |
548 | |
549 | info->hvc = hvc_alloc(HVC_COOKIE, info->irq, ops, 256); |
550 | if (IS_ERR(info->hvc)) { |
551 | r = PTR_ERR(info->hvc); |
552 | spin_lock(&xencons_lock); |
553 | list_del(&info->list); |
554 | spin_unlock(&xencons_lock); |
555 | if (info->irq) |
556 | unbind_from_irqhandler(info->irq, NULL); |
557 | kfree(info); |
558 | return r; |
559 | } |
560 | |
561 | r = 0; |
562 | #ifdef CONFIG_HVC_XEN_FRONTEND |
563 | r = xenbus_register_frontend(&xencons_driver); |
564 | #endif |
565 | return r; |
566 | } |
567 | device_initcall(xen_hvc_init); |
568 | |
569 | static int xen_cons_init(void) |
570 | { |
571 | const struct hv_ops *ops; |
572 | |
573 | if (!xen_domain()) |
574 | return 0; |
575 | |
576 | if (xen_initial_domain()) |
577 | ops = &dom0_hvc_ops; |
578 | else { |
579 | int r; |
580 | ops = &domU_hvc_ops; |
581 | |
582 | if (xen_hvm_domain()) |
583 | r = xen_hvm_console_init(); |
584 | else |
585 | r = xen_pv_console_init(); |
586 | if (r < 0) |
587 | return r; |
588 | } |
589 | |
590 | hvc_instantiate(HVC_COOKIE, 0, ops); |
591 | return 0; |
592 | } |
593 | console_initcall(xen_cons_init); |
594 | |
595 | #ifdef CONFIG_X86 |
596 | static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) |
597 | { |
598 | if (xen_cpuid_base()) |
599 | outsb(0xe9, str, len); |
600 | } |
601 | #else |
602 | static void xen_hvm_early_write(uint32_t vtermno, const char *str, int len) { } |
603 | #endif |
604 | |
605 | #ifdef CONFIG_EARLY_PRINTK |
606 | static int __init xenboot_setup_console(struct console *console, char *string) |
607 | { |
608 | static struct xencons_info xenboot; |
609 | |
610 | if (xen_initial_domain()) |
611 | return 0; |
612 | if (!xen_pv_domain()) |
613 | return -ENODEV; |
614 | |
615 | return xencons_info_pv_init(&xenboot, 0); |
616 | } |
617 | |
618 | static void xenboot_write_console(struct console *console, const char *string, |
619 | unsigned len) |
620 | { |
621 | unsigned int linelen, off = 0; |
622 | const char *pos; |
623 | |
624 | if (!xen_pv_domain()) { |
625 | xen_hvm_early_write(0, string, len); |
626 | return; |
627 | } |
628 | |
629 | dom0_write_console(0, string, len); |
630 | |
631 | if (xen_initial_domain()) |
632 | return; |
633 | |
634 | domU_write_console(0, "(early) " , 8); |
635 | while (off < len && NULL != (pos = strchr(string+off, '\n'))) { |
636 | linelen = pos-string+off; |
637 | if (off + linelen > len) |
638 | break; |
639 | domU_write_console(0, string+off, linelen); |
640 | domU_write_console(0, "\r\n" , 2); |
641 | off += linelen + 1; |
642 | } |
643 | if (off < len) |
644 | domU_write_console(0, string+off, len-off); |
645 | } |
646 | |
647 | struct console xenboot_console = { |
648 | .name = "xenboot" , |
649 | .write = xenboot_write_console, |
650 | .setup = xenboot_setup_console, |
651 | .flags = CON_PRINTBUFFER | CON_BOOT | CON_ANYTIME, |
652 | .index = -1, |
653 | }; |
654 | #endif /* CONFIG_EARLY_PRINTK */ |
655 | |
656 | void xen_raw_console_write(const char *str) |
657 | { |
658 | ssize_t len = strlen(str); |
659 | int rc = 0; |
660 | |
661 | if (xen_domain()) { |
662 | rc = dom0_write_console(0, str, len); |
663 | if (rc != -ENOSYS || !xen_hvm_domain()) |
664 | return; |
665 | } |
666 | xen_hvm_early_write(0, str, len); |
667 | } |
668 | |
669 | void xen_raw_printk(const char *fmt, ...) |
670 | { |
671 | static char buf[512]; |
672 | va_list ap; |
673 | |
674 | va_start(ap, fmt); |
675 | vsnprintf(buf, sizeof(buf), fmt, ap); |
676 | va_end(ap); |
677 | |
678 | xen_raw_console_write(buf); |
679 | } |
680 | |
681 | static void xenboot_earlycon_write(struct console *console, |
682 | const char *string, |
683 | unsigned len) |
684 | { |
685 | dom0_write_console(0, string, len); |
686 | } |
687 | |
688 | static int __init xenboot_earlycon_setup(struct earlycon_device *device, |
689 | const char *opt) |
690 | { |
691 | device->con->write = xenboot_earlycon_write; |
692 | return 0; |
693 | } |
694 | EARLYCON_DECLARE(xenboot, xenboot_earlycon_setup); |
695 | |