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Re: [Qemu-devel] [PATCH v4 2/7] fw-cfg: turn FW_CFG_FILE_SLOTS into a de
From: |
Gerd Hoffmann |
Subject: |
Re: [Qemu-devel] [PATCH v4 2/7] fw-cfg: turn FW_CFG_FILE_SLOTS into a device property |
Date: |
Fri, 02 Dec 2016 12:10:38 +0100 |
On Do, 2016-12-01 at 18:06 +0100, Laszlo Ersek wrote:
> We'd like to raise the value of FW_CFG_FILE_SLOTS. Doing it naively could
> lead to problems with backward migration: a more recent QEMU (running an
> older machine type) would allow the guest, in fw_cfg_select(), to select a
> high key value that is unavailable in the same machine type implemented by
> the older (target) QEMU.
I don't think we need this. fw_cfg changes are guest-visible so they
must not happen for a given machine type. So if current machine types
don't hit the limit that should continue to be the case even if we
simply raise FW_CFG_FILE_SLOTS.
But we have to take care that new files show up on new machine types
only.
cheers,
Gerd
[Qemu-devel] [PATCH v4 2/7] fw-cfg: turn FW_CFG_FILE_SLOTS into a device property, Laszlo Ersek, 2016/12/01
- Re: [Qemu-devel] [PATCH v4 2/7] fw-cfg: turn FW_CFG_FILE_SLOTS into a device property,
Gerd Hoffmann <=
Re: [Qemu-devel] [PATCH v4 2/7] fw-cfg: turn FW_CFG_FILE_SLOTS into a device property, Igor Mammedov, 2016/12/06
[Qemu-devel] [PATCH v4 4/7] hw/i386/pc: introduce 2.9 machine types with 0x20 fw_cfg file slots, Laszlo Ersek, 2016/12/01
[Qemu-devel] [PATCH v4 6/7] hw/isa/lpc_ich9: add broadcast SMI feature, Laszlo Ersek, 2016/12/01
[Qemu-devel] [PATCH v4 1/7] fw-cfg: support writeable blobs, Laszlo Ersek, 2016/12/01