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Re: [Qemu-devel] [PATCH v2 5/6] atapi: GESN: implement 'media' subcomman
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [PATCH v2 5/6] atapi: GESN: implement 'media' subcommand |
Date: |
Tue, 12 Apr 2011 12:41:16 +0200 |
User-agent: |
Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.15) Gecko/20101027 Fedora/3.0.10-1.fc12 Thunderbird/3.0.10 |
Am 12.04.2011 11:27, schrieb Amit Shah:
> Implement the 'media' sub-command of the GET_EVENT_STATUS_NOTIFICATION
> command. This helps us report tray open, tray closed, no media, media
> present states to the guest.
>
> Newer Linux kernels (2.6.38+) rely on this command to revalidate discs
> after media change.
>
> This patch also sends out tray open/closed status to the guest driver
> when requested e.g. via the CDROM_DRIVE_STATUS ioctl (thanks Markus).
> Without such notification, the guest and qemu's tray open/close status
> was frequently out of sync, causing installers like Anaconda detecting
> no disc instead of tray open, confusing them terribly.
>
> Signed-off-by: Amit Shah <address@hidden>
> ---
> hw/ide/core.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++-
> hw/ide/internal.h | 6 +++
> 2 files changed, 96 insertions(+), 2 deletions(-)
>
> diff --git a/hw/ide/core.c b/hw/ide/core.c
> index fe50d8a..2683070 100644
> --- a/hw/ide/core.c
> +++ b/hw/ide/core.c
> @@ -1084,6 +1084,47 @@ static int ide_dvd_read_structure(IDEState *s, int
> format,
> }
> }
>
> +static unsigned int event_status_media(IDEState *s,
> + uint8_t *buf,
> + unsigned int max_len,
> + unsigned int event_class,
> + unsigned int supported_events)
> +{
> + enum media_event_code {
> + no_change = 0, /* Status unchanged */
> + eject_requested, /* received a request from user to eject */
> + new_media, /* new media inserted and ready for access */
> + media_removal, /* only for media changers */
> + media_changed, /* only for media changers */
> + bg_format_completed, /* MRW or DVD+RW b/g format completed */
> + bg_format_restarted, /* MRW or DVD+RW b/g format restarted */
> + };
> + enum media_status {
> + tray_open = 1,
> + media_present = 2,
> + };
> + uint8_t event_code, media_status;
> +
> + media_status = 0;
> + if (s->bs->tray_open) {
> + media_status = tray_open;
> + } else if (bdrv_is_inserted(s->bs)) {
> + media_status = media_present;
> + }
> +
> + /* Event notification descriptor */
> + event_code = no_change;
> + if (media_status != tray_open && s->events.new_media) {
> + event_code = new_media;
> + s->events.new_media = false;
> + }
> +
> + buf[4] = event_code;
> + buf[5] = media_status;
> +
> + return 6; /* We wrote to just 2 extra bytes from the header */
I must admit that I don't understand your answer you gave on v1 here.
Let me quote:
>> > After media_state, there are two more fields for start/end slot (even
>> > though they are reserved because we don't have a multiple slot device)
> Yes, they're reserved, so we shouldn't change them. Any change might
> trigger bad response from guests.
I'm not sure what we would be _changing_. We're building a response
structure here, not modifying existing data.
So what your code does is to receive a short response that leaves out
the reserved fields. I don't think this is how it's supposed to work. We
should include the reserved fields in the descriptor length and zero
them (MMC-5, section 3.6.8):
"“Reserved” is a keyword referring to bits, bytes, words, fields and
code values that are set aside for future standardization. A reserved
bit, byte, word or field shall be set to zero, or in accordance with a
future extension to this standard."
> +}
> +
> static unsigned int event_status_nea(uint8_t *buf, unsigned int max_len)
> {
> cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
> @@ -1107,7 +1148,28 @@ static void
> handle_get_event_status_notification(IDEState *s,
> uint8_t len_lsb;
> uint8_t control;
> } __attribute__((packed)) *gesn_cdb;
> + enum notification_class_request_type {
> + reserved1 = 1 << 0,
> + operational_change = 1 << 1,
> + power_management = 1 << 2,
> + external_request = 1 << 3,
> + media = 1 << 4,
> + multi_host = 1 << 5,
> + device_busy = 1 << 6,
> + reserved2 = 1 << 7,
> + };
> + enum event_notification_class_field {
> + enc_no_events = 0,
> + enc_operational_change,
> + enc_power_management,
> + enc_external_request,
> + enc_media,
> + enc_multiple_hosts,
> + enc_device_busy,
> + enc_reserved,
> + };
> unsigned int max_len, used_len;
> + unsigned int supported_events;
>
> gesn_cdb = (void *)packet;
> max_len = ube16_to_cpu(&gesn_cdb->len_msb);
> @@ -1122,8 +1184,33 @@ static void
> handle_get_event_status_notification(IDEState *s,
>
> /* polling mode operation */
>
> - /* We don't support any event class (yet). */
> - used_len = event_status_nea(buf, max_len);
> + /*
> + * These are the supported events.
> + *
> + * We currently only support requests of the 'media' type.
> + */
> + supported_events = media;
> +
> + /*
> + * Event notification header; will be overwritten by the
> + * NO_EVENT_AVAILABLE code if we don't have events: according to
> + * MMC-5 6.7.2.2, if nea = 1, event class field should be 0.
> + */
> + cpu_to_ube16(buf, max_len);
That doesn't look right. I think it needs to be used_len - sizeof(header).
> + buf[2] = event_class;
> + buf[3] = supported_events;
The spec doesn't talk about "event class" for buf[2], but about
"notification class" (same applies for the comment above). We should
stick to that as buf[3] is called "supported event class", so they might
be confused.
> +
> + /*
> + * Responses to requests are to be based on request priority. The
> + * notification_class_request_type enum above specifies the
> + * priority: upper elements are higher prio than lower ones.
> + */
> + if (gesn_cdb->request & media) {
> + used_len = event_status_media(s, buf, max_len, enc_media,
> + supported_events);
> + } else {
> + used_len = event_status_nea(buf, max_len);
This expands to:
cpu_to_ube16(buf, 0x00); /* No event descriptor returned */
buf[2] = 0x80; /* No Event Available (NEA) */
buf[3] = 0x00; /* Empty supported event classes */
The first one is covered if you fix what I mentioned above (used_len -
sizeof(header)). The third one is wrong, we still support the media
class. So what is left is one line:
buf[2] = 0x80; /* No Event Available (NEA) */
I'm still not convinced that having event_status_nea() as a separate
function makes a lot of sense.
> + }
> ide_atapi_cmd_reply(s, used_len, max_len);
> }
>
> @@ -1650,6 +1737,7 @@ static void cdrom_change_cb(void *opaque, int reason)
> s->sense_key = SENSE_UNIT_ATTENTION;
> s->asc = ASC_MEDIUM_MAY_HAVE_CHANGED;
> s->cdrom_changed = 1;
> + s->events.new_media = true;
> ide_set_irq(s->bus);
> }
>
> diff --git a/hw/ide/internal.h b/hw/ide/internal.h
> index d533fb6..ba7e9a8 100644
> --- a/hw/ide/internal.h
> +++ b/hw/ide/internal.h
> @@ -373,6 +373,11 @@ typedef int DMAFunc(IDEDMA *);
> typedef int DMAIntFunc(IDEDMA *, int);
> typedef void DMARestartFunc(void *, int, int);
>
> +struct unreported_events {
> + bool eject_request;
> + bool new_media;
> +};
> +
> /* NOTE: IDEState represents in fact one drive */
> struct IDEState {
> IDEBus *bus;
> @@ -408,6 +413,7 @@ struct IDEState {
> BlockDriverState *bs;
> char version[9];
> /* ATAPI specific */
> + struct unreported_events events;
> uint8_t sense_key;
> uint8_t asc;
> uint8_t cdrom_changed;
Kevin
- [Qemu-devel] [PATCH v2 0/6] atapi: Implement 'media' subcommand for GESN, Amit Shah, 2011/04/12
- [Qemu-devel] [PATCH v2 1/6] atapi: Allow GESN after media change, Amit Shah, 2011/04/12
- [Qemu-devel] [PATCH v2 3/6] atapi: GESN: Spin off No Event Available handling into own function, Amit Shah, 2011/04/12
- [Qemu-devel] [PATCH v2 2/6] atapi: Move GET_EVENT_STATUS_NOTIFICATION command handling to its own function, Amit Shah, 2011/04/12
- [Qemu-devel] [PATCH v2 4/6] atapi: GESN: Use structs for commonly-used field types, Amit Shah, 2011/04/12
- [Qemu-devel] [PATCH v2 5/6] atapi: GESN: implement 'media' subcommand, Amit Shah, 2011/04/12
- Re: [Qemu-devel] [PATCH v2 5/6] atapi: GESN: implement 'media' subcommand,
Kevin Wolf <=
- [Qemu-devel] [PATCH v2 6/6] atapi: Save / load the new GESN event states during migration, Amit Shah, 2011/04/12