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Re: [Qemu-devel] [PATCH v4 06/07] s390: sclp ascii console support
From: |
Alexander Graf |
Subject: |
Re: [Qemu-devel] [PATCH v4 06/07] s390: sclp ascii console support |
Date: |
Mon, 30 Jul 2012 16:02:16 +0200 |
On 26.07.2012, at 10:55, Christian Borntraeger wrote:
> From: Heinz Graalfs <address@hidden>
>
> This code adds console support by implementing SCLP's ASCII Console
> Data event. This is the same console as LPARs ASCII console or z/VMs
> sysascii.
>
> The console can be specified manually with something like
> -chardev stdio,id=charconsole0 -device
> sclpconsole,chardev=charconsole0,id=console0
>
> Newer kernels will autodetect that console and prefer that over virtio
> console.
>
> When data is received from the character layer it creates a service
> interrupt to trigger a Read Event Data command from the guest that will
> pick up the received character byte-stream.
> When characters are echo'ed by the linux guest a Write Event Data occurs
> which is forwarded by the Event Facility to the console that supports
> a corresponding mask value.
> Console resizing is not supported.
> The character layer byte-stream is buffered using a fixed size iov
> buffer.
>
> changes in v4: fold in suggestions by blueswirl
>
> Signed-off-by: Heinz Graalfs <address@hidden>
> Signed-off-by: Christian Borntraeger <address@hidden>
> ---
> hw/s390x/Makefile.objs | 2 +-
> hw/s390x/sclpconsole.c | 323 ++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 324 insertions(+), 1 deletions(-)
> create mode 100644 hw/s390x/sclpconsole.c
>
> diff --git a/hw/s390x/Makefile.objs b/hw/s390x/Makefile.objs
> index ed4e61a..096dfcd 100644
> --- a/hw/s390x/Makefile.objs
> +++ b/hw/s390x/Makefile.objs
> @@ -3,4 +3,4 @@ obj-y = s390-virtio-bus.o s390-virtio.o
> obj-y := $(addprefix ../,$(obj-y))
> obj-y += sclp.o
> obj-y += event-facility.o
> -obj-y += sclpquiesce.o
> +obj-y += sclpquiesce.o sclpconsole.o
> diff --git a/hw/s390x/sclpconsole.c b/hw/s390x/sclpconsole.c
> new file mode 100644
> index 0000000..c77b2a1
> --- /dev/null
> +++ b/hw/s390x/sclpconsole.c
> @@ -0,0 +1,323 @@
> +/*
> + * SCLP event type
> + * Ascii Console Data (VT220 Console)
> + *
> + * Copyright IBM, Corp. 2012
> + *
> + * Authors:
> + * Heinz Graalfs <address@hidden>
> + *
> + * This work is licensed under the terms of the GNU GPL, version 2 or (at
> your
> + * option) any later version. See the COPYING file in the top-level
> directory.
> + *
> + */
> +
> +#include <hw/qdev.h>
> +#include "qemu-thread.h"
> +
> +#include "sclp.h"
> +#include "event-facility.h"
> +
> +typedef struct ASCIIConsoleData {
> + EventBufferHeader ebh;
> + char data[0];
> +} QEMU_PACKED ASCIIConsoleData;
> +
> +/* max size for ASCII data in 4K SCCB page */
> +#define SIZE_BUFFER_VT220 4080
> +
> +typedef struct SCLPConsole {
> + SCLPEvent event;
> + CharDriverState *chr;
> + /* io vector */
> + uint8_t *iov; /* iov buffer pointer */
> + uint8_t *iov_sclp; /* pointer to SCLP read offset */
> + uint8_t *iov_bs; /* pointer byte stream read offset */
> + uint32_t iov_data_len; /* length of byte stream in buffer */
> + uint32_t iov_sclp_rest; /* length of byte stream not read via SCLP */
> + qemu_irq sclp_read_vt220;
I'm sure this one wants a name that indicates it's an irq line ;)
> +} SCLPConsole;
> +
> +/* character layer call-back functions */
> +
> +/* Return number of bytes that fit into iov buffer */
> +static int chr_can_read(void *opaque)
> +{
> + int can_read;
> + SCLPConsole *scon = opaque;
> +
> + qemu_mutex_lock(&scon->event.lock);
Explicit locks now?
> + can_read = SIZE_BUFFER_VT220 - scon->iov_data_len;
> + qemu_mutex_unlock(&scon->event.lock);
> +
> + return can_read;
> +}
> +
> +/* Receive n bytes from character layer, save in iov buffer,
> + * and set event pending */
> +static void receive_from_chr_layer(SCLPConsole *scon, const uint8_t *buf,
> + int size)
> +{
> + assert(scon->iov);
> +
> + qemu_mutex_lock(&scon->event.lock);
> +
> + /* if new data do not fit into current buffer */
> + if (scon->iov_data_len + size > SIZE_BUFFER_VT220) {
> + /* character layer sent more than allowed */
> + qemu_mutex_unlock(&scon->event.lock);
> + return;
So we drop the bytes it did send? Isn't there usually some can_read function
from the char layer that we can indicate to that we have enough space?
If so, then this should be an assert(), right?
> + }
> + /* put byte-stream from character layer into buffer */
> + memcpy(scon->iov_bs, buf, size);
> + scon->iov_data_len += size;
> + scon->iov_sclp_rest += size;
> + scon->iov_bs += size;
> + scon->event.event_pending = true;
> +
> + qemu_mutex_unlock(&scon->event.lock);
> +}
> +
> +/* Send data from a char device over to the guest */
> +static void chr_read(void *opaque, const uint8_t *buf, int size)
> +{
> + SCLPConsole *scon = opaque;
> +
> + assert(scon);
> +
> + receive_from_chr_layer(scon, buf, size);
> + /* trigger SCLP read operation */
> + qemu_irq_raise(scon->sclp_read_vt220);
> +}
> +
> +static void chr_event(void *opaque, int event)
> +{
> + SCLPConsole *scon = opaque;
> +
> + switch (event) {
> + case CHR_EVENT_OPENED:
> + if (!scon->iov) {
> + scon->iov = g_malloc0(SIZE_BUFFER_VT220);
> + scon->iov_sclp = scon->iov;
> + scon->iov_bs = scon->iov;
> + scon->iov_data_len = 0;
> + scon->iov_sclp_rest = 0;
> + }
> + break;
> + case CHR_EVENT_CLOSED:
> + if (scon->iov) {
> + g_free(scon->iov);
> + scon->iov = NULL;
> + }
> + break;
> + }
> +}
> +
> +/* functions to be called by event facility */
> +
> +static int event_type(void)
> +{
> + return SCLP_EVENT_ASCII_CONSOLE_DATA;
> +}
> +
> +static unsigned int send_mask(void)
> +{
> + return SCLP_EVENT_MASK_MSG_ASCII;
> +}
> +
> +static unsigned int receive_mask(void)
> +{
> + return SCLP_EVENT_MASK_MSG_ASCII;
> +}
> +
> +/* triggered by SCLP's read_event_data -
> + * copy console data byte-stream into provided (SCLP) buffer
> + */
> +static void get_console_data(SCLPEvent *event, uint8_t *buf, size_t *size,
> + int avail)
> +{
> + SCLPConsole *cons = DO_UPCAST(SCLPConsole, event, event);
> +
> + /* first byte is hex 0 saying an ascii string follows */
> + *buf++ = '\0';
> + avail--;
> + /* if all data fit into provided SCLP buffer */
> + if (avail >= cons->iov_sclp_rest) {
> + /* copy character byte-stream to SCLP buffer */
> + memcpy(buf, cons->iov_sclp, cons->iov_sclp_rest);
> + *size = cons->iov_sclp_rest + 1;
> + cons->iov_sclp = cons->iov;
> + cons->iov_bs = cons->iov;
> + cons->iov_data_len = 0;
> + cons->iov_sclp_rest = 0;
> + event->event_pending = false;
> + /* data provided and no more data pending */
> + } else {
> + /* if provided buffer is too small, just copy part */
> + memcpy(buf, cons->iov_sclp, avail);
> + *size = avail + 1;
> + cons->iov_sclp_rest -= avail;
> + cons->iov_sclp += avail;
> + /* more data pending */
> + }
> +}
I'm wondering whether we actually need this indirection from
chr layer -> buffer -> sclp buffer.
Why can't we just do
chr layer -> sclp buffer?
Alex
- Re: [Qemu-devel] [PATCH v4 07/07] s390: make sclp ascii console the default, (continued)
[Qemu-devel] [PATCH 4/7] s390: sclp event support, Christian Borntraeger, 2012/07/24
Re: [Qemu-devel] [PATCH 4/7] s390: sclp event support, Andreas Färber, 2012/07/31
[Qemu-devel] [PATCH 6/7] s390: sclp ascii console support, Christian Borntraeger, 2012/07/24
[Qemu-devel] [PATCH 5/7] s390: sclp signal quiesce support, Christian Borntraeger, 2012/07/24
[Qemu-devel] [PATCH 3/7] s390: sclp base support, Christian Borntraeger, 2012/07/24
[Qemu-devel] [PATCH 1/7] s390: Fix error handling and condition code of service call, Christian Borntraeger, 2012/07/24
[Qemu-devel] [PATCH 2/7] s390: provide interface for service interrupt/introduce interrupt.c, Christian Borntraeger, 2012/07/24
Re: [Qemu-devel] [PATCH 0/7v3] s390: sclp patch set, Christian Borntraeger, 2012/07/30