[librm] Ensure that inline code symbols are unique
[ipxe.git] / src / arch / x86 / interface / syslinux / comboot_call.c
1 /*
2 * Copyright (C) 2008 Daniel Verkamp <daniel@drv.nu>.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation; either version 2 of the
7 * License, or any later version.
8 *
9 * This program is distributed in the hope that it will be useful, but
10 * WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
17 * 02110-1301, USA.
18 */
19
20 /**
21 * @file SYSLINUX COMBOOT API
22 *
23 */
24
25 FILE_LICENCE ( GPL2_OR_LATER );
26
27 #include <errno.h>
28 #include <realmode.h>
29 #include <biosint.h>
30 #include <ipxe/console.h>
31 #include <stdlib.h>
32 #include <comboot.h>
33 #include <bzimage.h>
34 #include <pxe_call.h>
35 #include <rmsetjmp.h>
36 #include <string.h>
37 #include <ipxe/posix_io.h>
38 #include <ipxe/process.h>
39 #include <ipxe/serial.h>
40 #include <ipxe/init.h>
41 #include <ipxe/image.h>
42 #include <ipxe/version.h>
43 #include <usr/imgmgmt.h>
44
45 /** The "SYSLINUX" version string */
46 static char __bss16_array ( syslinux_version, [32] );
47 #define syslinux_version __use_data16 ( syslinux_version )
48
49 /** The "SYSLINUX" copyright string */
50 static char __data16_array ( syslinux_copyright, [] ) = " http://ipxe.org";
51 #define syslinux_copyright __use_data16 ( syslinux_copyright )
52
53 static char __data16_array ( syslinux_configuration_file, [] ) = "";
54 #define syslinux_configuration_file __use_data16 ( syslinux_configuration_file )
55
56 /** Feature flags */
57 static uint8_t __data16 ( comboot_feature_flags ) = COMBOOT_FEATURE_IDLE_LOOP;
58 #define comboot_feature_flags __use_data16 ( comboot_feature_flags )
59
60 typedef union {
61 syslinux_pm_regs pm; syslinux_rm_regs rm;
62 } syslinux_regs;
63
64 /** Initial register values for INT 22h AX=1Ah and 1Bh */
65 static syslinux_regs __text16 ( comboot_initial_regs );
66 #define comboot_initial_regs __use_text16 ( comboot_initial_regs )
67
68 static struct segoff __text16 ( int20_vector );
69 #define int20_vector __use_text16 ( int20_vector )
70
71 static struct segoff __text16 ( int21_vector );
72 #define int21_vector __use_text16 ( int21_vector )
73
74 static struct segoff __text16 ( int22_vector );
75 #define int22_vector __use_text16 ( int22_vector )
76
77 extern void int20_wrapper ( void );
78 extern void int21_wrapper ( void );
79 extern void int22_wrapper ( void );
80
81 /* setjmp/longjmp context buffer used to return after loading an image */
82 rmjmp_buf comboot_return;
83
84 /* Mode flags set by INT 22h AX=0017h */
85 static uint16_t comboot_graphics_mode = 0;
86
87 /**
88 * Print a string with a particular terminator
89 */
90 static void print_user_string ( unsigned int segment, unsigned int offset, char terminator ) {
91 int i = 0;
92 char c;
93 userptr_t str = real_to_user ( segment, offset );
94 for ( ; ; ) {
95 copy_from_user ( &c, str, i, 1 );
96 if ( c == terminator ) break;
97 putchar ( c );
98 i++;
99 }
100 }
101
102
103 /**
104 * Perform a series of memory copies from a list in low memory
105 */
106 static void shuffle ( unsigned int list_segment, unsigned int list_offset, unsigned int count )
107 {
108 comboot_shuffle_descriptor shuf[COMBOOT_MAX_SHUFFLE_DESCRIPTORS];
109 unsigned int i;
110
111 /* Copy shuffle descriptor list so it doesn't get overwritten */
112 copy_from_user ( shuf, real_to_user ( list_segment, list_offset ), 0,
113 count * sizeof( comboot_shuffle_descriptor ) );
114
115 /* Do the copies */
116 for ( i = 0; i < count; i++ ) {
117 userptr_t src_u = phys_to_user ( shuf[ i ].src );
118 userptr_t dest_u = phys_to_user ( shuf[ i ].dest );
119
120 if ( shuf[ i ].src == 0xFFFFFFFF ) {
121 /* Fill with 0 instead of copying */
122 memset_user ( dest_u, 0, 0, shuf[ i ].len );
123 } else if ( shuf[ i ].dest == 0xFFFFFFFF ) {
124 /* Copy new list of descriptors */
125 count = shuf[ i ].len / sizeof( comboot_shuffle_descriptor );
126 assert ( count <= COMBOOT_MAX_SHUFFLE_DESCRIPTORS );
127 copy_from_user ( shuf, src_u, 0, shuf[ i ].len );
128 i = -1;
129 } else {
130 /* Regular copy */
131 memmove_user ( dest_u, 0, src_u, 0, shuf[ i ].len );
132 }
133 }
134 }
135
136
137 /**
138 * Set default text mode
139 */
140 void comboot_force_text_mode ( void ) {
141 if ( comboot_graphics_mode & COMBOOT_VIDEO_VESA ) {
142 /* Set VGA mode 3 via VESA VBE mode set */
143 __asm__ __volatile__ (
144 REAL_CODE (
145 "mov $0x4F02, %%ax\n\t"
146 "mov $0x03, %%bx\n\t"
147 "int $0x10\n\t"
148 )
149 : : );
150 } else if ( comboot_graphics_mode & COMBOOT_VIDEO_GRAPHICS ) {
151 /* Set VGA mode 3 via standard VGA mode set */
152 __asm__ __volatile__ (
153 REAL_CODE (
154 "mov $0x03, %%ax\n\t"
155 "int $0x10\n\t"
156 )
157 : : );
158 }
159
160 comboot_graphics_mode = 0;
161 }
162
163
164 /**
165 * Fetch kernel and optional initrd
166 */
167 static int comboot_fetch_kernel ( char *kernel_file, char *cmdline ) {
168 struct image *kernel;
169 struct image *initrd;
170 char *initrd_file;
171 int rc;
172
173 /* Find initrd= parameter, if any */
174 if ( ( initrd_file = strstr ( cmdline, "initrd=" ) ) != NULL ) {
175 char *initrd_end;
176
177 /* skip "initrd=" */
178 initrd_file += 7;
179
180 /* Find terminating space, if any, and replace with NUL */
181 initrd_end = strchr ( initrd_file, ' ' );
182 if ( initrd_end )
183 *initrd_end = '\0';
184
185 DBG ( "COMBOOT: fetching initrd '%s'\n", initrd_file );
186
187 /* Fetch initrd */
188 if ( ( rc = imgdownload_string ( initrd_file, 0,
189 &initrd ) ) != 0 ) {
190 DBG ( "COMBOOT: could not fetch initrd: %s\n",
191 strerror ( rc ) );
192 return rc;
193 }
194
195 /* Restore space after initrd name, if applicable */
196 if ( initrd_end )
197 *initrd_end = ' ';
198 }
199
200 DBG ( "COMBOOT: fetching kernel '%s'\n", kernel_file );
201
202 /* Fetch kernel */
203 if ( ( rc = imgdownload_string ( kernel_file, 0, &kernel ) ) != 0 ) {
204 DBG ( "COMBOOT: could not fetch kernel: %s\n",
205 strerror ( rc ) );
206 return rc;
207 }
208
209 /* Replace comboot image with kernel */
210 if ( ( rc = image_replace ( kernel ) ) != 0 ) {
211 DBG ( "COMBOOT: could not replace with kernel: %s\n",
212 strerror ( rc ) );
213 return rc;
214 }
215
216 return 0;
217 }
218
219
220 /**
221 * Terminate program interrupt handler
222 */
223 static __asmcall void int20 ( struct i386_all_regs *ix86 __unused ) {
224 rmlongjmp ( comboot_return, COMBOOT_EXIT );
225 }
226
227
228 /**
229 * DOS-compatible API
230 */
231 static __asmcall void int21 ( struct i386_all_regs *ix86 ) {
232 ix86->flags |= CF;
233
234 switch ( ix86->regs.ah ) {
235 case 0x00:
236 case 0x4C: /* Terminate program */
237 rmlongjmp ( comboot_return, COMBOOT_EXIT );
238 break;
239
240 case 0x01: /* Get Key with Echo */
241 case 0x08: /* Get Key without Echo */
242 /* TODO: handle extended characters? */
243 ix86->regs.al = getchar( );
244
245 /* Enter */
246 if ( ix86->regs.al == 0x0A )
247 ix86->regs.al = 0x0D;
248
249 if ( ix86->regs.ah == 0x01 )
250 putchar ( ix86->regs.al );
251
252 ix86->flags &= ~CF;
253 break;
254
255 case 0x02: /* Write Character */
256 putchar ( ix86->regs.dl );
257 ix86->flags &= ~CF;
258 break;
259
260 case 0x04: /* Write Character to Serial Port */
261 if ( serial_console.base ) {
262 uart_transmit ( &serial_console, ix86->regs.dl );
263 ix86->flags &= ~CF;
264 }
265 break;
266
267 case 0x09: /* Write DOS String to Console */
268 print_user_string ( ix86->segs.ds, ix86->regs.dx, '$' );
269 ix86->flags &= ~CF;
270 break;
271
272 case 0x0B: /* Check Keyboard */
273 if ( iskey() )
274 ix86->regs.al = 0xFF;
275 else
276 ix86->regs.al = 0x00;
277
278 ix86->flags &= ~CF;
279 break;
280
281 case 0x30: /* Check DOS Version */
282 /* Bottom halves all 0; top halves spell "SYSLINUX" */
283 ix86->regs.eax = 0x59530000;
284 ix86->regs.ebx = 0x4C530000;
285 ix86->regs.ecx = 0x4E490000;
286 ix86->regs.edx = 0x58550000;
287 ix86->flags &= ~CF;
288 break;
289
290 default:
291 DBG ( "COMBOOT unknown int21 function %02x\n", ix86->regs.ah );
292 break;
293 }
294 }
295
296
297 /**
298 * Dispatch PXE API call weakly
299 *
300 * @v ix86 Registers for PXE call
301 * @ret present Zero if the PXE stack is present, nonzero if not
302 *
303 * A successful return only indicates that the PXE stack was available
304 * for dispatching the call; it says nothing about the success of
305 * whatever the call asked for.
306 */
307 __weak int pxe_api_call_weak ( struct i386_all_regs *ix86 __unused ) {
308 return -1;
309 }
310
311 /**
312 * SYSLINUX API
313 */
314 static __asmcall void int22 ( struct i386_all_regs *ix86 ) {
315 ix86->flags |= CF;
316
317 switch ( ix86->regs.ax ) {
318 case 0x0001: /* Get Version */
319
320 /* Number of INT 22h API functions available */
321 ix86->regs.ax = 0x001D;
322
323 /* SYSLINUX version number */
324 ix86->regs.ch = 0; /* major */
325 ix86->regs.cl = 0; /* minor */
326
327 /* SYSLINUX derivative ID */
328 ix86->regs.dl = BZI_LOADER_TYPE_IPXE;
329
330 /* SYSLINUX version */
331 snprintf ( syslinux_version, sizeof ( syslinux_version ),
332 "\r\niPXE %s", product_version );
333
334 /* SYSLINUX version and copyright strings */
335 ix86->segs.es = rm_ds;
336 ix86->regs.si = ( ( unsigned ) __from_data16 ( syslinux_version ) );
337 ix86->regs.di = ( ( unsigned ) __from_data16 ( syslinux_copyright ) );
338
339 ix86->flags &= ~CF;
340 break;
341
342 case 0x0002: /* Write String */
343 print_user_string ( ix86->segs.es, ix86->regs.bx, '\0' );
344 ix86->flags &= ~CF;
345 break;
346
347 case 0x0003: /* Run command */
348 {
349 userptr_t cmd_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
350 int len = strlen_user ( cmd_u, 0 );
351 char cmd[len + 1];
352 copy_from_user ( cmd, cmd_u, 0, len + 1 );
353 DBG ( "COMBOOT: executing command '%s'\n", cmd );
354 system ( cmd );
355 DBG ( "COMBOOT: exiting after executing command...\n" );
356 rmlongjmp ( comboot_return, COMBOOT_EXIT_COMMAND );
357 }
358 break;
359
360 case 0x0004: /* Run default command */
361 /* FIXME: just exit for now */
362 rmlongjmp ( comboot_return, COMBOOT_EXIT_COMMAND );
363 break;
364
365 case 0x0005: /* Force text mode */
366 comboot_force_text_mode ( );
367 ix86->flags &= ~CF;
368 break;
369
370 case 0x0006: /* Open file */
371 {
372 int fd;
373 userptr_t file_u = real_to_user ( ix86->segs.es, ix86->regs.si );
374 int len = strlen_user ( file_u, 0 );
375 char file[len + 1];
376
377 copy_from_user ( file, file_u, 0, len + 1 );
378
379 if ( file[0] == '\0' ) {
380 DBG ( "COMBOOT: attempted open with empty file name\n" );
381 break;
382 }
383
384 DBG ( "COMBOOT: opening file '%s'\n", file );
385
386 fd = open ( file );
387
388 if ( fd < 0 ) {
389 DBG ( "COMBOOT: error opening file %s\n", file );
390 break;
391 }
392
393 /* This relies on the fact that a iPXE POSIX fd will
394 * always fit in 16 bits.
395 */
396 #if (POSIX_FD_MAX > 65535)
397 #error POSIX_FD_MAX too large
398 #endif
399 ix86->regs.si = (uint16_t) fd;
400
401 ix86->regs.cx = COMBOOT_FILE_BLOCKSZ;
402 ix86->regs.eax = fsize ( fd );
403 ix86->flags &= ~CF;
404 }
405 break;
406
407 case 0x0007: /* Read file */
408 {
409 int fd = ix86->regs.si;
410 int len = ix86->regs.cx * COMBOOT_FILE_BLOCKSZ;
411 int rc;
412 fd_set fds;
413 userptr_t buf = real_to_user ( ix86->segs.es, ix86->regs.bx );
414
415 /* Wait for data ready to read */
416 FD_ZERO ( &fds );
417 FD_SET ( fd, &fds );
418
419 select ( &fds, 1 );
420
421 rc = read_user ( fd, buf, 0, len );
422 if ( rc < 0 ) {
423 DBG ( "COMBOOT: read failed\n" );
424 ix86->regs.si = 0;
425 break;
426 }
427
428 ix86->regs.ecx = rc;
429 ix86->flags &= ~CF;
430 }
431 break;
432
433 case 0x0008: /* Close file */
434 {
435 int fd = ix86->regs.si;
436 close ( fd );
437 ix86->flags &= ~CF;
438 }
439 break;
440
441 case 0x0009: /* Call PXE Stack */
442 if ( pxe_api_call_weak ( ix86 ) != 0 )
443 ix86->flags |= CF;
444 else
445 ix86->flags &= ~CF;
446 break;
447
448 case 0x000A: /* Get Derivative-Specific Information */
449
450 /* iPXE has its own derivative ID, so there is no defined
451 * output here; just return AL for now */
452 ix86->regs.al = BZI_LOADER_TYPE_IPXE;
453 ix86->flags &= ~CF;
454 break;
455
456 case 0x000B: /* Get Serial Console Configuration */
457 if ( serial_console.base ) {
458 ix86->regs.dx = ( ( intptr_t ) serial_console.base );
459 ix86->regs.cx = serial_console.divisor;
460 ix86->regs.bx = 0;
461 ix86->flags &= ~CF;
462 }
463 break;
464
465 case 0x000C: /* Perform final cleanup */
466 shutdown_boot();
467 break;
468
469 case 0x000E: /* Get configuration file name */
470 /* FIXME: stub */
471 ix86->segs.es = rm_ds;
472 ix86->regs.bx = ( ( unsigned ) __from_data16 ( syslinux_configuration_file ) );
473 ix86->flags &= ~CF;
474 break;
475
476 case 0x000F: /* Get IPAPPEND strings */
477 /* FIXME: stub */
478 ix86->regs.cx = 0;
479 ix86->segs.es = 0;
480 ix86->regs.bx = 0;
481 ix86->flags &= ~CF;
482 break;
483
484 case 0x0010: /* Resolve hostname */
485 {
486 userptr_t hostname_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
487 int len = strlen_user ( hostname_u, 0 );
488 char hostname[len];
489 struct in_addr addr;
490
491 copy_from_user ( hostname, hostname_u, 0, len + 1 );
492
493 /* TODO:
494 * "If the hostname does not contain a dot (.), the
495 * local domain name is automatically appended."
496 */
497
498 comboot_resolv ( hostname, &addr );
499
500 ix86->regs.eax = addr.s_addr;
501 ix86->flags &= ~CF;
502 }
503 break;
504
505 case 0x0011: /* Maximum number of shuffle descriptors */
506 ix86->regs.cx = COMBOOT_MAX_SHUFFLE_DESCRIPTORS;
507 ix86->flags &= ~CF;
508 break;
509
510 case 0x0012: /* Cleanup, shuffle and boot */
511 if ( ix86->regs.cx > COMBOOT_MAX_SHUFFLE_DESCRIPTORS )
512 break;
513
514 /* Perform final cleanup */
515 shutdown_boot();
516
517 /* Perform sequence of copies */
518 shuffle ( ix86->segs.es, ix86->regs.di, ix86->regs.cx );
519
520 /* Jump to real-mode entry point */
521 __asm__ __volatile__ (
522 REAL_CODE (
523 "pushw %0\n\t"
524 "popw %%ds\n\t"
525 "pushl %1\n\t"
526 "lret\n\t"
527 )
528 :
529 : "r" ( ix86->segs.ds ),
530 "r" ( ix86->regs.ebp ),
531 "d" ( ix86->regs.ebx ),
532 "S" ( ix86->regs.esi ) );
533
534 assert ( 0 ); /* Execution should never reach this point */
535
536 break;
537
538 case 0x0013: /* Idle loop call */
539 step ( );
540 ix86->flags &= ~CF;
541 break;
542
543 case 0x0015: /* Get feature flags */
544 ix86->segs.es = rm_ds;
545 ix86->regs.bx = ( ( unsigned ) __from_data16 ( &comboot_feature_flags ) );
546 ix86->regs.cx = 1; /* Number of feature flag bytes */
547 ix86->flags &= ~CF;
548 break;
549
550 case 0x0016: /* Run kernel image */
551 {
552 userptr_t file_u = real_to_user ( ix86->segs.ds, ix86->regs.si );
553 userptr_t cmd_u = real_to_user ( ix86->segs.es, ix86->regs.bx );
554 int file_len = strlen_user ( file_u, 0 );
555 int cmd_len = strlen_user ( cmd_u, 0 );
556 char file[file_len + 1];
557 char cmd[cmd_len + 1];
558
559 copy_from_user ( file, file_u, 0, file_len + 1 );
560 copy_from_user ( cmd, cmd_u, 0, cmd_len + 1 );
561
562 DBG ( "COMBOOT: run kernel %s %s\n", file, cmd );
563 comboot_fetch_kernel ( file, cmd );
564 /* Technically, we should return if we
565 * couldn't load the kernel, but it's not safe
566 * to do that since we have just overwritten
567 * part of the COMBOOT program's memory space.
568 */
569 DBG ( "COMBOOT: exiting to run kernel...\n" );
570 rmlongjmp ( comboot_return, COMBOOT_EXIT_RUN_KERNEL );
571 }
572 break;
573
574 case 0x0017: /* Report video mode change */
575 comboot_graphics_mode = ix86->regs.bx;
576 ix86->flags &= ~CF;
577 break;
578
579 case 0x0018: /* Query custom font */
580 /* FIXME: stub */
581 ix86->regs.al = 0;
582 ix86->segs.es = 0;
583 ix86->regs.bx = 0;
584 ix86->flags &= ~CF;
585 break;
586
587 case 0x001B: /* Cleanup, shuffle and boot to real mode */
588 if ( ix86->regs.cx > COMBOOT_MAX_SHUFFLE_DESCRIPTORS )
589 break;
590
591 /* Perform final cleanup */
592 shutdown_boot();
593
594 /* Perform sequence of copies */
595 shuffle ( ix86->segs.es, ix86->regs.di, ix86->regs.cx );
596
597 /* Copy initial register values to .text16 */
598 memcpy_user ( real_to_user ( rm_cs, (unsigned) __from_text16 ( &comboot_initial_regs ) ), 0,
599 real_to_user ( ix86->segs.ds, ix86->regs.si ), 0,
600 sizeof(syslinux_rm_regs) );
601
602 /* Load initial register values */
603 __asm__ __volatile__ (
604 REAL_CODE (
605 /* Point SS:SP at the register value structure */
606 "pushw %%cs\n\t"
607 "popw %%ss\n\t"
608 "movw $comboot_initial_regs, %%sp\n\t"
609
610 /* Segment registers */
611 "popw %%es\n\t"
612 "popw %%ax\n\t" /* Skip CS */
613 "popw %%ds\n\t"
614 "popw %%ax\n\t" /* Skip SS for now */
615 "popw %%fs\n\t"
616 "popw %%gs\n\t"
617
618 /* GP registers */
619 "popl %%eax\n\t"
620 "popl %%ecx\n\t"
621 "popl %%edx\n\t"
622 "popl %%ebx\n\t"
623 "popl %%ebp\n\t" /* Skip ESP for now */
624 "popl %%ebp\n\t"
625 "popl %%esi\n\t"
626 "popl %%edi\n\t"
627
628 /* Load correct SS:ESP */
629 "movw $(comboot_initial_regs + 6), %%sp\n\t"
630 "popw %%ss\n\t"
631 "movl %%cs:(comboot_initial_regs + 28), %%esp\n\t"
632
633 "ljmp *%%cs:(comboot_initial_regs + 44)\n\t"
634 )
635 : : );
636
637 break;
638
639 case 0x001C: /* Get pointer to auxilliary data vector */
640 /* FIXME: stub */
641 ix86->regs.cx = 0; /* Size of the ADV */
642 ix86->flags &= ~CF;
643 break;
644
645 case 0x001D: /* Write auxilliary data vector */
646 /* FIXME: stub */
647 ix86->flags &= ~CF;
648 break;
649
650 default:
651 DBG ( "COMBOOT unknown int22 function %04x\n", ix86->regs.ax );
652 break;
653 }
654 }
655
656 /**
657 * Hook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h)
658 */
659 void hook_comboot_interrupts ( ) {
660
661 __asm__ __volatile__ (
662 TEXT16_CODE ( "\nint20_wrapper:\n\t"
663 VIRT_CALL ( int20 )
664 "clc\n\t"
665 "call patch_cf\n\t"
666 "iret\n\t" ) : );
667
668 hook_bios_interrupt ( 0x20, ( intptr_t ) int20_wrapper, &int20_vector );
669
670 __asm__ __volatile__ (
671 TEXT16_CODE ( "\nint21_wrapper:\n\t"
672 VIRT_CALL ( int21 )
673 "clc\n\t"
674 "call patch_cf\n\t"
675 "iret\n\t" ) : );
676
677 hook_bios_interrupt ( 0x21, ( intptr_t ) int21_wrapper, &int21_vector );
678
679 __asm__ __volatile__ (
680 TEXT16_CODE ( "\nint22_wrapper:\n\t"
681 VIRT_CALL ( int22 )
682 "clc\n\t"
683 "call patch_cf\n\t"
684 "iret\n\t" ) : );
685
686 hook_bios_interrupt ( 0x22, ( intptr_t ) int22_wrapper, &int22_vector );
687 }
688
689 /**
690 * Unhook BIOS interrupts related to COMBOOT API (INT 20h, 21h, 22h)
691 */
692 void unhook_comboot_interrupts ( ) {
693
694 unhook_bios_interrupt ( 0x20, ( intptr_t ) int20_wrapper,
695 &int20_vector );
696
697 unhook_bios_interrupt ( 0x21, ( intptr_t ) int21_wrapper,
698 &int21_vector );
699
700 unhook_bios_interrupt ( 0x22, ( intptr_t ) int22_wrapper,
701 &int22_vector );
702 }
703
704 /* Avoid dragging in serial console support unconditionally */
705 struct uart serial_console __attribute__ (( weak ));