qemu-patch-raspberry4/include/chardev/char.h
Anton Nefedov 7bb86085e6 char: chardevice hotswap
This patch adds a possibility to change a char device without a frontend
removal.

Ideally, it would have to happen transparently to a frontend, i.e.
frontend would continue its regular operation.
However, backends are not stateless and are set up by the frontends
via qemu_chr_fe_<> functions, and it's not (generally) possible to replay
that setup entirely in a backend code, as different chardevs respond
to the setup calls differently, so do frontends work differently basing
on those setup responses.
Moreover, some frontend can generally get and save the backend pointer
(qemu_chr_fe_get_driver()), and it will become invalid after backend change.

So, a frontend which would like to support chardev hotswap has to register
a "backend change" handler, and redo its backend setup there.

Signed-off-by: Anton Nefedov <anton.nefedov@virtuozzo.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>
Message-Id: <1499342940-56739-4-git-send-email-anton.nefedov@virtuozzo.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2017-07-14 11:04:33 +02:00

239 lines
6.9 KiB
C

#ifndef QEMU_CHAR_H
#define QEMU_CHAR_H
#include "qemu-common.h"
#include "qemu/option.h"
#include "qemu/main-loop.h"
#include "qemu/bitmap.h"
#include "qom/object.h"
#define IAC_EOR 239
#define IAC_SE 240
#define IAC_NOP 241
#define IAC_BREAK 243
#define IAC_IP 244
#define IAC_SB 250
#define IAC 255
/* character device */
typedef struct CharBackend CharBackend;
typedef enum {
CHR_EVENT_BREAK, /* serial break char */
CHR_EVENT_OPENED, /* new connection established */
CHR_EVENT_MUX_IN, /* mux-focus was set to this terminal */
CHR_EVENT_MUX_OUT, /* mux-focus will move on */
CHR_EVENT_CLOSED /* connection closed */
} QEMUChrEvent;
#define CHR_READ_BUF_LEN 4096
typedef enum {
/* Whether the chardev peer is able to close and
* reopen the data channel, thus requiring support
* for qemu_chr_wait_connected() to wait for a
* valid connection */
QEMU_CHAR_FEATURE_RECONNECTABLE,
/* Whether it is possible to send/recv file descriptors
* over the data channel */
QEMU_CHAR_FEATURE_FD_PASS,
/* Whether replay or record mode is enabled */
QEMU_CHAR_FEATURE_REPLAY,
QEMU_CHAR_FEATURE_LAST,
} ChardevFeature;
#define qemu_chr_replay(chr) qemu_chr_has_feature(chr, QEMU_CHAR_FEATURE_REPLAY)
struct Chardev {
Object parent_obj;
QemuMutex chr_write_lock;
CharBackend *be;
char *label;
char *filename;
int logfd;
int be_open;
GSource *gsource;
DECLARE_BITMAP(features, QEMU_CHAR_FEATURE_LAST);
};
/**
* @qemu_chr_new_from_opts:
*
* Create a new character backend from a QemuOpts list.
*
* @opts see qemu-config.c for a list of valid options
*
* Returns: a new character backend
*/
Chardev *qemu_chr_new_from_opts(QemuOpts *opts,
Error **errp);
/**
* @qemu_chr_parse_common:
*
* Parse the common options available to all character backends.
*
* @opts the options that still need parsing
* @backend a new backend
*/
void qemu_chr_parse_common(QemuOpts *opts, ChardevCommon *backend);
/**
* @qemu_chr_new:
*
* Create a new character backend from a URI.
*
* @label the name of the backend
* @filename the URI
*
* Returns: a new character backend
*/
Chardev *qemu_chr_new(const char *label, const char *filename);
/**
* @qemu_chr_change:
*
* Change an existing character backend
*
* @opts the new backend options
*/
void qemu_chr_change(QemuOpts *opts, Error **errp);
/**
* @qemu_chr_cleanup:
*
* Delete all chardevs (when leaving qemu)
*/
void qemu_chr_cleanup(void);
/**
* @qemu_chr_new_noreplay:
*
* Create a new character backend from a URI.
* Character device communications are not written
* into the replay log.
*
* @label the name of the backend
* @filename the URI
*
* Returns: a new character backend
*/
Chardev *qemu_chr_new_noreplay(const char *label, const char *filename);
/**
* @qemu_chr_be_can_write:
*
* Determine how much data the front end can currently accept. This function
* returns the number of bytes the front end can accept. If it returns 0, the
* front end cannot receive data at the moment. The function must be polled
* to determine when data can be received.
*
* Returns: the number of bytes the front end can receive via @qemu_chr_be_write
*/
int qemu_chr_be_can_write(Chardev *s);
/**
* @qemu_chr_be_write:
*
* Write data from the back end to the front end. Before issuing this call,
* the caller should call @qemu_chr_be_can_write to determine how much data
* the front end can currently accept.
*
* @buf a buffer to receive data from the front end
* @len the number of bytes to receive from the front end
*/
void qemu_chr_be_write(Chardev *s, uint8_t *buf, int len);
/**
* @qemu_chr_be_write_impl:
*
* Implementation of back end writing. Used by replay module.
*
* @buf a buffer to receive data from the front end
* @len the number of bytes to receive from the front end
*/
void qemu_chr_be_write_impl(Chardev *s, uint8_t *buf, int len);
/**
* @qemu_chr_be_event:
*
* Send an event from the back end to the front end.
*
* @event the event to send
*/
void qemu_chr_be_event(Chardev *s, int event);
int qemu_chr_add_client(Chardev *s, int fd);
Chardev *qemu_chr_find(const char *name);
bool qemu_chr_has_feature(Chardev *chr,
ChardevFeature feature);
void qemu_chr_set_feature(Chardev *chr,
ChardevFeature feature);
QemuOpts *qemu_chr_parse_compat(const char *label, const char *filename);
int qemu_chr_write(Chardev *s, const uint8_t *buf, int len, bool write_all);
#define qemu_chr_write_all(s, buf, len) qemu_chr_write(s, buf, len, true)
int qemu_chr_wait_connected(Chardev *chr, Error **errp);
#define TYPE_CHARDEV "chardev"
#define CHARDEV(obj) OBJECT_CHECK(Chardev, (obj), TYPE_CHARDEV)
#define CHARDEV_CLASS(klass) \
OBJECT_CLASS_CHECK(ChardevClass, (klass), TYPE_CHARDEV)
#define CHARDEV_GET_CLASS(obj) \
OBJECT_GET_CLASS(ChardevClass, (obj), TYPE_CHARDEV)
#define TYPE_CHARDEV_NULL "chardev-null"
#define TYPE_CHARDEV_MUX "chardev-mux"
#define TYPE_CHARDEV_RINGBUF "chardev-ringbuf"
#define TYPE_CHARDEV_PTY "chardev-pty"
#define TYPE_CHARDEV_CONSOLE "chardev-console"
#define TYPE_CHARDEV_STDIO "chardev-stdio"
#define TYPE_CHARDEV_PIPE "chardev-pipe"
#define TYPE_CHARDEV_MEMORY "chardev-memory"
#define TYPE_CHARDEV_PARALLEL "chardev-parallel"
#define TYPE_CHARDEV_FILE "chardev-file"
#define TYPE_CHARDEV_SERIAL "chardev-serial"
#define TYPE_CHARDEV_SOCKET "chardev-socket"
#define TYPE_CHARDEV_UDP "chardev-udp"
#define CHARDEV_IS_RINGBUF(chr) \
object_dynamic_cast(OBJECT(chr), TYPE_CHARDEV_RINGBUF)
#define CHARDEV_IS_PTY(chr) \
object_dynamic_cast(OBJECT(chr), TYPE_CHARDEV_PTY)
typedef struct ChardevClass {
ObjectClass parent_class;
bool internal; /* TODO: eventually use TYPE_USER_CREATABLE */
void (*parse)(QemuOpts *opts, ChardevBackend *backend, Error **errp);
void (*open)(Chardev *chr, ChardevBackend *backend,
bool *be_opened, Error **errp);
int (*chr_write)(Chardev *s, const uint8_t *buf, int len);
int (*chr_sync_read)(Chardev *s, const uint8_t *buf, int len);
GSource *(*chr_add_watch)(Chardev *s, GIOCondition cond);
void (*chr_update_read_handler)(Chardev *s, GMainContext *context);
int (*chr_ioctl)(Chardev *s, int cmd, void *arg);
int (*get_msgfds)(Chardev *s, int* fds, int num);
int (*set_msgfds)(Chardev *s, int *fds, int num);
int (*chr_add_client)(Chardev *chr, int fd);
int (*chr_wait_connected)(Chardev *chr, Error **errp);
void (*chr_disconnect)(Chardev *chr);
void (*chr_accept_input)(Chardev *chr);
void (*chr_set_echo)(Chardev *chr, bool echo);
void (*chr_set_fe_open)(Chardev *chr, int fe_open);
} ChardevClass;
Chardev *qemu_chardev_new(const char *id, const char *typename,
ChardevBackend *backend, Error **errp);
extern int term_escape_char;
/* console.c */
void qemu_chr_parse_vc(QemuOpts *opts, ChardevBackend *backend, Error **errp);
#endif