forked from luck/tmp_suning_uos_patched
virtio: console: comment cleanup
Remove old lguest-style comments.
[Amit: - wingify comments acc. to kernel style
- indent comments ]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell
parent
3b8706240e
commit
a23ea92474
@ -1,18 +1,5 @@
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/*D:300
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* The Guest console driver
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*
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* Writing console drivers is one of the few remaining Dark Arts in Linux.
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* Fortunately for us, the path of virtual consoles has been well-trodden by
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* the PowerPC folks, who wrote "hvc_console.c" to generically support any
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* virtual console. We use that infrastructure which only requires us to write
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* the basic put_chars and get_chars functions and call the right register
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* functions.
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:*/
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/*M:002 The console can be flooded: while the Guest is processing input the
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* Host can send more. Buffering in the Host could alleviate this, but it is a
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* difficult problem in general. :*/
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/* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
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/*
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* Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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@ -34,8 +21,6 @@
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#include <linux/virtio_console.h>
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#include "hvc_console.h"
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/*D:340 These represent our input and output console queues, and the virtio
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* operations for them. */
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static struct virtqueue *in_vq, *out_vq;
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static struct virtio_device *vdev;
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@ -49,12 +34,14 @@ static struct hv_ops virtio_cons;
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/* The hvc device */
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static struct hvc_struct *hvc;
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/*D:310 The put_chars() callback is pretty straightforward.
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/*
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* The put_chars() callback is pretty straightforward.
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*
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* We turn the characters into a scatter-gather list, add it to the output
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* queue and then kick the Host. Then we sit here waiting for it to finish:
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* inefficient in theory, but in practice implementations will do it
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* immediately (lguest's Launcher does). */
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* We turn the characters into a scatter-gather list, add it to the
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* output queue and then kick the Host. Then we sit here waiting for
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* it to finish: inefficient in theory, but in practice
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* implementations will do it immediately (lguest's Launcher does).
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*/
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static int put_chars(u32 vtermno, const char *buf, int count)
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{
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struct scatterlist sg[1];
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@ -63,8 +50,10 @@ static int put_chars(u32 vtermno, const char *buf, int count)
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/* This is a convenient routine to initialize a single-elem sg list */
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sg_init_one(sg, buf, count);
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/* add_buf wants a token to identify this buffer: we hand it any
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* non-NULL pointer, since there's only ever one buffer. */
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/*
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* add_buf wants a token to identify this buffer: we hand it
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* any non-NULL pointer, since there's only ever one buffer.
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*/
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if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) {
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/* Tell Host to go! */
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out_vq->vq_ops->kick(out_vq);
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@ -77,8 +66,10 @@ static int put_chars(u32 vtermno, const char *buf, int count)
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return count;
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}
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/* Create a scatter-gather list representing our input buffer and put it in the
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* queue. */
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/*
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* Create a scatter-gather list representing our input buffer and put
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* it in the queue.
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*/
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static void add_inbuf(void)
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{
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struct scatterlist sg[1];
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@ -90,12 +81,14 @@ static void add_inbuf(void)
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in_vq->vq_ops->kick(in_vq);
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}
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/*D:350 get_chars() is the callback from the hvc_console infrastructure when
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* an interrupt is received.
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/*
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* get_chars() is the callback from the hvc_console infrastructure
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* when an interrupt is received.
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*
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* Most of the code deals with the fact that the hvc_console() infrastructure
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* only asks us for 16 bytes at a time. We keep in_offset and in_used fields
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* for partially-filled buffers. */
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* Most of the code deals with the fact that the hvc_console()
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* infrastructure only asks us for 16 bytes at a time. We keep
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* in_offset and in_used fields for partially-filled buffers.
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*/
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static int get_chars(u32 vtermno, char *buf, int count)
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{
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/* If we don't have an input queue yet, we can't get input. */
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@ -123,14 +116,16 @@ static int get_chars(u32 vtermno, char *buf, int count)
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return count;
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}
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/*:*/
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/*D:320 Console drivers are initialized very early so boot messages can go out,
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* so we do things slightly differently from the generic virtio initialization
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* of the net and block drivers.
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/*
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* Console drivers are initialized very early so boot messages can go
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* out, so we do things slightly differently from the generic virtio
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* initialization of the net and block drivers.
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*
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* At this stage, the console is output-only. It's too early to set up a
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* virtqueue, so we let the drivers do some boutique early-output thing. */
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* At this stage, the console is output-only. It's too early to set
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* up a virtqueue, so we let the drivers do some boutique early-output
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* thing.
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*/
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int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
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{
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virtio_cons.put_chars = put_chars;
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@ -157,8 +152,8 @@ static void virtcons_apply_config(struct virtio_device *dev)
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}
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/*
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* we support only one console, the hvc struct is a global var
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* We set the configuration at this point, since we now have a tty
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* we support only one console, the hvc struct is a global var We set
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* the configuration at this point, since we now have a tty
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*/
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static int notifier_add_vio(struct hvc_struct *hp, int data)
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{
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@ -179,13 +174,17 @@ static void hvc_handle_input(struct virtqueue *vq)
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hvc_kick();
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}
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/*D:370 Once we're further in boot, we get probed like any other virtio device.
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* At this stage we set up the output virtqueue.
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/*
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* Once we're further in boot, we get probed like any other virtio
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* device. At this stage we set up the output virtqueue.
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*
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* To set up and manage our virtual console, we call hvc_alloc(). Since we
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* never remove the console device we never need this pointer again.
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* To set up and manage our virtual console, we call hvc_alloc().
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* Since we never remove the console device we never need this pointer
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* again.
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*
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* Finally we put our input buffer in the input queue, ready to receive. */
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* Finally we put our input buffer in the input queue, ready to
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* receive.
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*/
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static int __devinit virtcons_probe(struct virtio_device *dev)
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{
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vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
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@ -203,8 +202,6 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
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}
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/* Find the queues. */
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/* FIXME: This is why we want to wean off hvc: we do nothing
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* when input comes in. */
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err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
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if (err)
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goto free;
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@ -219,15 +216,18 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
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virtio_cons.notifier_del = notifier_del_vio;
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virtio_cons.notifier_hangup = notifier_del_vio;
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/* The first argument of hvc_alloc() is the virtual console number, so
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* we use zero. The second argument is the parameter for the
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* notification mechanism (like irq number). We currently leave this
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* as zero, virtqueues have implicit notifications.
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/*
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* The first argument of hvc_alloc() is the virtual console
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* number, so we use zero. The second argument is the
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* parameter for the notification mechanism (like irq
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* number). We currently leave this as zero, virtqueues have
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* implicit notifications.
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*
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* The third argument is a "struct hv_ops" containing the put_chars()
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* get_chars(), notifier_add() and notifier_del() pointers.
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* The final argument is the output buffer size: we can do any size,
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* so we put PAGE_SIZE here. */
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* The third argument is a "struct hv_ops" containing the
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* put_chars(), get_chars(), notifier_add() and notifier_del()
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* pointers. The final argument is the output buffer size: we
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* can do any size, so we put PAGE_SIZE here.
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*/
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hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE);
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if (IS_ERR(hvc)) {
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err = PTR_ERR(hvc);
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@ -3,8 +3,10 @@
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#include <linux/types.h>
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#include <linux/virtio_ids.h>
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#include <linux/virtio_config.h>
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/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
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* anyone can use the definitions to implement compatible drivers/servers. */
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/*
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* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
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* anyone can use the definitions to implement compatible drivers/servers.
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*/
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/* Feature bits */
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#define VIRTIO_CONSOLE_F_SIZE 0 /* Does host provide console size? */
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