Index: qemu/hw/ide/core.c
===================================================================
--- qemu.orig/hw/ide/core.c	2010-11-25 12:33:40.961255346 +0100
+++ qemu/hw/ide/core.c	2010-11-25 13:00:28.415005802 +0100
@@ -145,6 +145,8 @@ static void ide_identify(IDEState *s)
     put_le16(p + 66, 120);
     put_le16(p + 67, 120);
     put_le16(p + 68, 120);
+    if (dev && dev->conf.discard_granularity)
+        put_le16(p + 69, (1 << 14));	/* determinate TRIM behavior */
     put_le16(p + 80, 0xf0); /* ata3 -> ata6 supported */
     put_le16(p + 81, 0x16); /* conforms to ata5 */
     /* 14=NOP supported, 5=WCACHE supported, 0=SMART supported */
@@ -171,6 +173,8 @@ static void ide_identify(IDEState *s)
     dev = s->unit ? s->bus->slave : s->bus->master;
     if (dev && dev->conf.physical_block_size)
         put_le16(p + 106, 0x6000 | get_physical_block_exp(&dev->conf));
+    if (dev && dev->conf.discard_granularity)
+        put_le16(p + 169, 1);	/* TRIM support */
 
     memcpy(s->identify_data, p, sizeof(s->identify_data));
     s->identify_set = 1;
@@ -1787,6 +1791,128 @@ static void ide_clear_hob(IDEBus *bus)
     bus->ifs[1].select &= ~(1 << 7);
 }
 
+typedef struct TrimAIOCB {
+    BlockDriverAIOCB common;
+    QEMUBH *bh;
+    int ret;
+} TrimAIOCB;
+
+static void trim_aio_cancel(BlockDriverAIOCB *acb)
+{
+    TrimAIOCB *iocb = container_of(acb, TrimAIOCB, common);
+
+    qemu_bh_delete(iocb->bh);
+    iocb->bh = NULL;
+    qemu_aio_release(iocb);
+}
+
+static AIOPool trim_aio_pool = {
+    .aiocb_size         = sizeof(TrimAIOCB),
+    .cancel             = trim_aio_cancel,
+};
+
+static void ide_trim_bh_cb(void *opaque)
+{
+    TrimAIOCB *iocb = opaque;
+
+    iocb->common.cb(iocb->common.opaque, iocb->ret);
+
+    qemu_bh_delete(iocb->bh);
+    iocb->bh = NULL;
+
+    qemu_aio_release(iocb);
+}
+
+static BlockDriverAIOCB *ide_issue_trim(BlockDriverState *bs,
+        int64_t sector_num, QEMUIOVector *qiov, int nb_sectors,
+        BlockDriverCompletionFunc *cb, void *opaque)
+{
+    TrimAIOCB *iocb;
+    int i, j, ret;
+
+    iocb = qemu_aio_get(&trim_aio_pool, bs, cb, opaque);
+    iocb->bh = qemu_bh_new(ide_trim_bh_cb, iocb);
+    iocb->ret = 0;
+
+    for (j = 0; j < qiov->niov; j++) {
+        uint64_t *buffer = qiov->iov[j].iov_base;
+
+ 	for (i = 0; i < qiov->iov[j].iov_len / 8; i++) {
+		/* 6-byte LBA + 2-byte range per entry */
+		uint64_t entry = le64_to_cpu(buffer[i]);
+		uint64_t sector = entry & 0x0000ffffffffffffULL;
+		uint16_t count = entry >> 48;
+
+		if (count == 0)
+			 break;
+
+	        ret = bdrv_discard(bs, sector * 512, count * 512);
+                if (!iocb->ret)
+                    iocb->ret = ret;
+	}
+    }
+
+    qemu_bh_schedule(iocb->bh);
+
+    return &iocb->common;
+}
+
+static void ide_trim_dma_cb(void *opaque, int ret)
+{
+    BMDMAState *bm = opaque;
+    IDEState *s = bmdma_active_if(bm);
+    int n;
+    int64_t sector_num;
+
+    if (ret < 0) {
+        if (ide_handle_rw_error(s, -ret,  BM_STATUS_DMA_RETRY))
+            return;
+    }
+
+    n = s->io_buffer_size >> 9;
+    sector_num = ide_get_sector(s);
+    if (n > 0) {
+        dma_buf_commit(s, 0);
+        sector_num += n;
+        ide_set_sector(s, sector_num);
+        s->nsector -= n;
+    }
+
+    /* end of transfer ? */
+    if (s->nsector == 0) {
+        s->status = READY_STAT | SEEK_STAT;
+        ide_set_irq(s->bus);
+    eot:
+        bm->status &= ~BM_STATUS_DMAING;
+        bm->status |= BM_STATUS_INT;
+        bm->dma_cb = NULL;
+        bm->unit = -1;
+        bm->aiocb = NULL;
+        return;
+    }
+
+    n = s->nsector;
+    s->io_buffer_size = n * 512;
+    /* launch next transfer */
+    if (dma_buf_prepare(bm, 0) == 0)
+        goto eot;
+#ifdef DEBUG_AIO
+    printf("aio_write: sector_num=%" PRId64 " n=%d\n", sector_num, n);
+#endif
+    bm->aiocb = dma_bdrv_io(s->bs, &s->sg, sector_num, ide_issue_trim,
+                    ide_trim_dma_cb, bm, 1);
+    ide_dma_submit_check(s, ide_trim_dma_cb, bm);
+}
+
+static void ide_trim(IDEState *s)
+{
+    s->status = READY_STAT | SEEK_STAT | DRQ_STAT | BUSY_STAT;
+    s->io_buffer_index = 0;
+    s->io_buffer_size = 0;
+    s->is_read = 0;
+    ide_dma_start(s, ide_trim_dma_cb);
+}
+
 void ide_ioport_write(void *opaque, uint32_t addr, uint32_t val)
 {
     IDEBus *bus = opaque;
@@ -1866,6 +1992,17 @@ void ide_ioport_write(void *opaque, uint
             break;
 
         switch(val) {
+        case WIN_DSM:
+            switch (s->feature) {
+            case DSM_TRIM:
+                if (!s->bs)
+                   goto abort_cmd;
+                ide_trim(s);
+                break;
+            default:
+	        goto abort_cmd;
+            }
+            break;
         case WIN_IDENTIFY:
             if (s->bs && s->drive_kind != IDE_CD) {
                 if (s->drive_kind != IDE_CFATA)
Index: qemu/hw/ide/internal.h
===================================================================
--- qemu.orig/hw/ide/internal.h	2010-11-25 12:33:40.978254647 +0100
+++ qemu/hw/ide/internal.h	2010-11-25 12:39:16.668023539 +0100
@@ -59,7 +59,11 @@ typedef struct BMDMAState BMDMAState;
  */
 #define CFA_REQ_EXT_ERROR_CODE		0x03 /* CFA Request Extended Error Code */
 /*
- *	0x04->0x07 Reserved
+ *	0x04->0x05 Reserved
+ */
+#define WIN_DSM				0x06
+/*
+ *	0x07 Reserved
  */
 #define WIN_SRST			0x08 /* ATAPI soft reset command */
 #define WIN_DEVICE_RESET		0x08
@@ -187,6 +191,9 @@ typedef struct BMDMAState BMDMAState;
 
 #define IDE_DMA_BUF_SECTORS 256
 
+/* feature values for Data Set Management */
+#define DSM_TRIM			0x01
+
 #if (IDE_DMA_BUF_SECTORS < MAX_MULT_SECTORS)
 #error "IDE_DMA_BUF_SECTORS must be bigger or equal to MAX_MULT_SECTORS"
 #endif
Index: qemu/hw/ide/qdev.c
===================================================================
--- qemu.orig/hw/ide/qdev.c	2010-11-25 14:41:16.846004402 +0100
+++ qemu/hw/ide/qdev.c	2010-11-25 14:41:44.529062161 +0100
@@ -110,6 +110,11 @@ static int ide_drive_initfn(IDEDevice *d
     const char *serial;
     DriveInfo *dinfo;
 
+    if (dev->conf.discard_granularity && dev->conf.discard_granularity != 512) {
+        error_report("discard_granularity must be 512 for ide");
+        return -1;
+    }
+
     serial = dev->serial;
     if (!serial) {
         /* try to fall back to value set with legacy -drive serial=... */
