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Berrange" , Thomas Huth Subject: [RFC PATCH] qemu-options: try and clarify preferred block semantics Date: Fri, 19 Aug 2022 18:47:57 +0100 Message-Id: <20220819174757.3551361-1-alex.bennee@linaro.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Received-SPF: pass client-ip=2a00:1450:4864:20::32f; envelope-from=alex.bennee@linaro.org; helo=mail-wm1-x32f.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" 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 Cc: qemu-block@nongnu.org Cc: Kevin Wolf Cc: Hanna Reitz Cc: Daniel P. Berrange Cc: Thomas Huth Acked-by: Kevin Wolf Reviewed-by: Daniel P. Berrangé --- qemu-options.hx | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/qemu-options.hx b/qemu-options.hx index 3f23a42fa8..d57239d364 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 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)