--- scsi-disk.c.orig	2022-04-19 12:10:27.000000000 -0700
+++ scsi-disk.c	2022-07-25 17:00:49.000000000 -0700
@@ -2471,12 +2471,39 @@
          * dev->conf, qdev takes care of detaching on unplug. */
         dev->conf.blk = blk_new(qemu_get_aio_context(), 0, BLK_PERM_ALL);
         ret = blk_attach_dev(dev->conf.blk, &dev->qdev);
+        assert(!blkconf_blocksizes(&s->qdev.conf, errp));
         assert(ret == 0);
     }
 
     ctx = blk_get_aio_context(dev->conf.blk);
     aio_context_acquire(ctx);
-    s->qdev.blocksize = 2048;
+
+    /*
+     * While the convention is that SCSI CD drives have
+     * a default block size of 2048, due to hysterical
+     * raisins, SunOS 4 only works with drives that report a
+     * block size of 512 bytes. Apparently older machines
+     * had PROMs that short-sightedly assumed all SCSI
+     * disk devices would have have a sector size of 512
+     * bytes, and retrofitting all those fielded machines
+     * was deemed infeasible, so instead Sun shipped their
+     * own CD-ROM drives jumpered for a 512-byte sector
+     * size (and hard-coded the SunOS 4 CD-ROM driver to
+     * assume this). Using anything else triggers a DMA
+     * overrun error in the SunOS esp(4) SCSI driver.
+     *
+     * It would be nice if we could simulate the jumper
+     * setting by allowing the user to override the default
+     * block size from the command line, so we do that
+     * here instead of just rudely using a permanently
+     * hardcoded value of 2048.
+     */
+
+    if (s->qdev.conf.logical_block_size == 0)
+        s->qdev.blocksize = 2048;
+    else
+        s->qdev.blocksize = s->qdev.conf.logical_block_size;
+
     s->qdev.type = TYPE_ROM;
     s->features |= 1 << SCSI_DISK_F_REMOVABLE;
     if (!s->product) {