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Tue, 07 Jan 2025 23:28:34 -0800 (PST) Message-ID: Date: Wed, 8 Jan 2025 08:28:32 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 20/35] xen/console: introduce console_owner_domid() To: Stefano Stabellini Cc: Denis Mukhin , dmukhin@ford.com, xen-devel@lists.xenproject.org, Andrew Cooper , Julien Grall , Bertrand Marquis , Michal Orzel , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= References: <20241205-vuart-ns8250-v1-0-e9aa923127eb@ford.com> <20241205-vuart-ns8250-v1-20-e9aa923127eb@ford.com> <8a5a5a0f-72b0-4336-b0d2-142254319242@suse.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 08.01.2025 00:40, Stefano Stabellini wrote: > On Tue, 7 Jan 2025, Jan Beulich wrote: >> On 06.01.2025 19:48, Stefano Stabellini wrote: >>> On Mon, 6 Jan 2025, Jan Beulich wrote: >>>> On 04.01.2025 05:15, Denis Mukhin wrote: >>>>> >>>>> On Tuesday, December 10th, 2024 at 11:28 PM, Jan Beulich wrote: >>>>> >>>>>> >>>>>> >>>>>> On 06.12.2024 05:41, Denis Mukhin via B4 Relay wrote: >>>>>> >>>>>>> From: Denis Mukhin dmukhin@ford.com >>>>>>> >>>>>>> console_owner_domid() is introduced to obtain the "console owner" domain ID. >>>>>>> >>>>>>> The call is used in NS8250 emulator to identify the case when physical xen >>>>>>> console focus is owned by the domain w/ NS8250 emulator, in which case, >>>>>>> messages from guest OS are formatted w/o '(XEN)' prefix. >>>>>> >>>>>> >>>>>> Such messages ought to be processed through guest_printk(), which wants a >>>>>> domain pointer, not a domid_t anyway. Plus isn't that going to be >>>>>> current->domain anyway at the callsite, eliminating the need for such a >>>>>> >>>>>> helper altogether? >>>>> >>>>> If the current domain is owning the physical console and printing, say, Linux >>>>> login prompt, there's no need to add "(XEN)" for every printout; adding timestamps >>>>> can be disabled from Xen command line. >>>> >>>> Surely there shouldn't be (XEN), but without (d) it'll be ambiguous in a log >>>> which domain a message came from. As long as only Dom0 messages are left un- >>>> prefixed, that's likely fine. Yet as soon as multiple domains can issue such >>>> messages (and have console "focus") I think the prefix needs to be there. >>> >>> It looks like we are aligned on the desired behavior, >> >> Hmm, no, I don't think we are. I don't ... >> >>> but for clarity, >>> see https://marc.info/?l=xen-devel&m=173405161613716, also copy/pasted >>> here: >>> >>> I think we should provide a consistent behavior across architectures. >>> The current behavior with vpl011 and dom0less on ARM is the following: >>> >>> - no prefix for Dom0 output >>> - DOM$NUM for DomUs when not in focus, otherwise no prefix >> >> ... view this model as a desirable one. It leaves room for ambiguity. > > Adding a few more people in CC for feedback. > > My priority is to keep the architectures aligned. It might be OK to > change output format, but then let's do it uniformly on ARM as well. > > Jan, please clarify what you think would be better than the above. Is it > the following? I don't think I understood your preference. > > - DOM$NUM for Dom0 and DomUs when not in focus, otherwise no prefix No, I mean like we have it with guest_printk() today. (XEN) for Xen's own messages, (d) for ordinary domains' ones, and no prefix exclusively for the hardware/control domain. What is best to do when hardware and control domains are distinct I'm uncertain - I'd be inclined to suggest that the hardware domain then stay the one without any prefix. Jan