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Tue, 03 Jun 2025 00:09:14 -0700 (PDT) Message-ID: <93b76d35-7d08-4fc9-890a-4657004f226a@suse.com> Date: Tue, 3 Jun 2025 09:09:05 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] device-tree: Move Arm's static-evtchn feature to common To: "Orzel, Michal" Cc: Stefano Stabellini , Julien Grall , Bertrand Marquis , Volodymyr Babchuk , Andrew Cooper , Anthony PERARD , =?UTF-8?Q?Roger_Pau_Monn=C3=A9?= , xen-devel@lists.xenproject.org References: <20250527082117.120214-1-michal.orzel@amd.com> <344823d0-eb05-48e5-80c5-9598104f3a3b@suse.com> <28a9f398-d206-4e42-b627-bea71f038b4d@amd.com> <4a806a75-0a2a-45b9-8811-caa51321a6b8@amd.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: <4a806a75-0a2a-45b9-8811-caa51321a6b8@amd.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 03.06.2025 09:06, Orzel, Michal wrote: > > > On 03/06/2025 09:02, Jan Beulich wrote: >> On 03.06.2025 08:54, Orzel, Michal wrote: >>> >>> >>> On 02/06/2025 10:37, Jan Beulich wrote: >>>> On 27.05.2025 10:21, Michal Orzel wrote: >>>>> There's nothing Arm specific about this feature. Move it to common as >>>>> part of a larger activity to commonalize device tree related features. >>>>> For now, select it only for ARM until others (e.g. RISC-V) verify it >>>>> works for them too. >>>>> >>>>> Signed-off-by: Michal Orzel >>>> >>>> I realize this was already committed, but ... >>>> >>>>> --- a/xen/common/Kconfig >>>>> +++ b/xen/common/Kconfig >>>>> @@ -162,6 +162,14 @@ config STATIC_MEMORY >>>>> >>>>> If unsure, say N. >>>>> >>>>> +config STATIC_EVTCHN >>>>> + bool "Static event channel support on a dom0less system" >>>>> + depends on DOM0LESS_BOOT && ARM >>>> >>>> ... I think we should strive to avoid such arch dependencies; they simply >>>> don't scale very well. Instead (if needed) HAS_* should be introduced, which >>>> each interested arch can select. In the case here, however, perhaps >>>> DOM0LESS_BOOT alone would have been sufficient as a dependency? >>> What if e.g. RISC-V wants to enable dom0less but not static evtchn/memory/shmem >>> because there are some functions to be implemented and they don't want to do it >>> now? Protecting with just DOM0LESS_BOOT would not be sufficient here. >> >> Imo a transient(!) "depends on !RISCV" would in principle be fine, if ... > In this case, how can I know that upfront? When moving a feature I need to put > some dependencies. At that point I don't know RISCV, PPC plans. You don't need to know this up front, do you? Neither of the two presently selects DOM0LESS_BOOT afaict, and hence such a transient negative dependency would (if necessary in the first place) be added when adding such a select. Jan