From 5af2b0f6eace7b368ed5cad9677e3bc995b6a7e3 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Alex=20Benn=C3=A9e?= Date: Mon, 22 Aug 2022 17:56:08 +0100 Subject: [PATCH] qemu-options: try and clarify preferred block semantics MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Try to correct any confusion about QEMU's Byzantine disk options by laying out the preferred "modern" options as-per: " (best: -device + -blockdev, 2nd obsolete syntax: -device + -drive, 3rd obsolete syntax: -drive, 4th obsolete syntax: -hdNN)" Signed-off-by: Alex Bennée Acked-by: Kevin Wolf Reviewed-by: Daniel P. Berrangé Cc: qemu-block@nongnu.org Cc: Kevin Wolf Cc: Hanna Reitz Cc: Thomas Huth Message-Id: <20220822165608.2980552-7-alex.bennee@linaro.org> --- qemu-options.hx | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/qemu-options.hx b/qemu-options.hx index 3f23a42fa8..31c04f7eea 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -1105,6 +1105,19 @@ DEFHEADING() DEFHEADING(Block device options:) +SRST +The QEMU block device handling options have a long history and +have gone through several iterations as the feature set and complexity +of the block layer have grown. Many online guides to QEMU often +reference older and deprecated options, which can lead to confusion. + +The recommended modern way to describe disks is to use a combination of +``-device`` to specify the hardware device and ``-blockdev`` to +describe the backend. The device defines what the guest sees and the +backend describes how QEMU handles the data. + +ERST + DEF("fda", HAS_ARG, QEMU_OPTION_fda, "-fda/-fdb file use 'file' as floppy disk 0/1 image\n", QEMU_ARCH_ALL) DEF("fdb", HAS_ARG, QEMU_OPTION_fdb, "", QEMU_ARCH_ALL)