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GET /api/patches/1882153/?format=api
{ "id": 1882153, "url": "http://patchwork.ozlabs.org/api/patches/1882153/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20240103173349.398526-44-alex.bennee@linaro.org/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20240103173349.398526-44-alex.bennee@linaro.org>", "list_archive_url": null, "date": "2024-01-03T17:33:49", "name": "[v2,43/43] docs/devel: document some plugin assumptions", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "fbdb2362517f38016a6a709ffb19e23ab9683119", "submitter": { "id": 39532, "url": "http://patchwork.ozlabs.org/api/people/39532/?format=api", "name": "Alex Bennée", "email": "alex.bennee@linaro.org" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20240103173349.398526-44-alex.bennee@linaro.org/mbox/", "series": [ { "id": 388742, "url": "http://patchwork.ozlabs.org/api/series/388742/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=388742", "date": "2024-01-03T17:33:08", "name": "testing and plugin updates for 9.0 (pre-PR)", "version": 2, "mbox": "http://patchwork.ozlabs.org/series/388742/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/1882153/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/1882153/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=linaro.org header.i=@linaro.org header.a=rsa-sha256\n header.s=google header.b=M/XA8ZIV;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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Iglesias\" <edgar.iglesias@gmail.com>,\n Eduardo Habkost <eduardo@habkost.net>,\n Pierrick Bouvier <pierrick.bouvier@linaro.org>, qemu-riscv@nongnu.org,\n Alistair Francis <alistair.francis@wdc.com>", "Subject": "[PATCH v2 43/43] docs/devel: document some plugin assumptions", "Date": "Wed, 3 Jan 2024 17:33:49 +0000", "Message-Id": "<20240103173349.398526-44-alex.bennee@linaro.org>", "X-Mailer": "git-send-email 2.39.2", "In-Reply-To": "<20240103173349.398526-1-alex.bennee@linaro.org>", "References": "<20240103173349.398526-1-alex.bennee@linaro.org>", "MIME-Version": "1.0", "Content-Type": "text/plain; charset=UTF-8", "Content-Transfer-Encoding": "8bit", "Received-SPF": "pass client-ip=2a00:1450:4864:20::430;\n envelope-from=alex.bennee@linaro.org; helo=mail-wr1-x430.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,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001,\n T_SCC_BODY_TEXT_LINE=-0.01 autolearn=unavailable autolearn_force=no", "X-Spam_action": "no action", "X-BeenThere": "qemu-devel@nongnu.org", "X-Mailman-Version": "2.1.29", "Precedence": "list", "List-Id": "<qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "While we attempt to hide implementation details from the plugin we\nshouldn't be totally obtuse. Let the user know what they can and can't\nexpect with the various instrumentation options.\n\nSigned-off-by: Alex Bennée <alex.bennee@linaro.org>\n---\n docs/devel/tcg-plugins.rst | 49 ++++++++++++++++++++++++++++++++++++++\n 1 file changed, 49 insertions(+)", "diff": "diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst\nindex 535a74684c5..9cc09d8c3da 100644\n--- a/docs/devel/tcg-plugins.rst\n+++ b/docs/devel/tcg-plugins.rst\n@@ -112,6 +112,55 @@ details are opaque to plugins. The plugin is able to query select\n details of instructions and system configuration only through the\n exported *qemu_plugin* functions.\n \n+However the following assumptions can be made:\n+\n+Translation Blocks\n+++++++++++++++++++\n+\n+All code will go through a translation phase although not all\n+translations will be necessarily be executed. You need to instrument\n+actual executions to track what is happening.\n+\n+It is quite normal to see the same address translated multiple times.\n+If you want to track the code in system emulation you should examine\n+the underlying physical address (``qemu_plugin_insn_haddr``) to take\n+into account the effects of virtual memory although if the system does\n+paging this will change too.\n+\n+Not all instructions in a block will always execute so if its\n+important to track individual instruction execution you need to\n+instrument them directly. However asynchronous interrupts will not\n+change control flow mid-block.\n+\n+Instructions\n+++++++++++++\n+\n+Instruction instrumentation runs before the instruction executes. You\n+can be can be sure the instruction will be dispatched, but you can't\n+be sure it will complete. Generally this will be because of a\n+synchronous exception (e.g. SIGILL) triggered by the instruction\n+attempting to execute. If you want to be sure you will need to\n+instrument the next instruction as well. See the ``execlog.c`` plugin\n+for examples of how to track this and finalise details after execution.\n+\n+Memory Accesses\n++++++++++++++++\n+\n+Memory callbacks are called after a successful load or store.\n+Unsuccessful operations (i.e. faults) will not be visible to memory\n+instrumentation although the execution side effects can be observed\n+(e.g. entering a exception handler).\n+\n+System Idle and Resume States\n++++++++++++++++++++++++++++++\n+\n+The ``qemu_plugin_register_vcpu_idle_cb`` and\n+``qemu_plugin_register_vcpu_resume_cb`` functions can be used to track\n+when CPUs go into and return from sleep states when waiting for\n+external I/O. Be aware though that these may occur less frequently\n+than in real HW due to the inefficiencies of emulation giving less\n+chance for the CPU to idle.\n+\n Internals\n ---------\n \n", "prefixes": [ "v2", "43/43" ] }