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authorBernhard Beschow <shentey@gmail.com>2022-05-13 20:09:56 +0200
committerAnthony PERARD <anthony.perard@citrix.com>2022-06-09 14:47:42 +0100
commit36902417460e3f9f1c63a79d802622fd774f1c30 (patch)
tree2349f253b9b294a4549e47792fb9859a8640a0b3
parent7851b21a8192750adecbcf6e8780a20de5891ad6 (diff)
hw/ide/piix: Add some documentation to pci_piix3_xen_ide_unplug()
The comment is based on commit message ae4d2eb273b167dad748ea4249720319240b1ac2 'xen-platform: add missing disk unplug option'. Since it seems to describe design decisions and limitations that still apply it seems worth having. Signed-off-by: Bernhard Beschow <shentey@gmail.com> Reviewed-by: Anthony PERARD <anthony.perard@citrix.com> Message-Id: <20220513180957.90514-3-shentey@gmail.com> Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
-rw-r--r--hw/ide/piix.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/hw/ide/piix.c b/hw/ide/piix.c
index 2345fe9e1d..bc1b37512a 100644
--- a/hw/ide/piix.c
+++ b/hw/ide/piix.c
@@ -173,6 +173,17 @@ static void pci_piix_ide_realize(PCIDevice *dev, Error **errp)
}
}
+/*
+ * The Xen HVM unplug protocol [1] specifies a mechanism to allow guests to
+ * request unplug of 'aux' disks (which is stated to mean all IDE disks,
+ * except the primary master).
+ *
+ * NOTE: The semantics of what happens if unplug of all disks and 'aux' disks
+ * is simultaneously requested is not clear. The implementation assumes
+ * that an 'all' request overrides an 'aux' request.
+ *
+ * [1] https://xenbits.xen.org/gitweb/?p=xen.git;a=blob;f=docs/misc/hvm-emulated-unplug.pandoc
+ */
int pci_piix3_xen_ide_unplug(DeviceState *dev, bool aux)
{
PCIIDEState *pci_ide;