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Wed, 27 May 2026 13:44:29 +0000 (GMT) Received: from osiris (unknown [9.52.214.206]) by smtpav04.fra02v.mail.ibm.com (Postfix) with ESMTPS; Wed, 27 May 2026 13:44:29 +0000 (GMT) Date: Wed, 27 May 2026 15:44:28 +0200 From: Heiko Carstens To: Miguel Ojeda Cc: Alice Ryhl , Boqun Feng , Jan Polensky , gor@linux.ibm.com, agordeev@linux.ibm.com, ojeda@kernel.org, peterz@infradead.org, jpoimboe@kernel.org, jbaron@akamai.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, tmgross@umich.edu, dakr@kernel.org, rostedt@goodmis.org, ardb@kernel.org, linux-s390@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 0/4] s390: Enable Rust support and add required arch glue Message-ID: <20260527134428.9471C69-hca@linux.ibm.com> References: <20260521165622.279953-1-japo@linux.ibm.com> <20260526161312.19291A8f-hca@linux.ibm.com> Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTI3MDEzMyBTYWx0ZWRfXylGDjg00c0YN ZB4d6CSRojRKHAe4qUeqJzWJLzaiWixnzpKxKFaVweteCpdftO8HuUx8SoA/c6PSp0qs7DMabyr iwl8Ci0pnu49IeaMG1t7WDyyxcse0WtQsidync/dzqK1X469o0DtGBu3wAOJv0K/t8pnJLEEV3k R0Yu0fj9dwoPyQFas3gKVHZ0nAlSRzb5DZCqz1yoOiohHmn1FESsxPVWHq93HHllBDUZJIzuSEz 8mcAOkcIS6dpKCuK8PzNqIZUtH64A726CgGJGItb78xojPjHekS9MVJkvhhKn6nPZAbCr8la21S A+m15GIAhLPW5hQOBgRnqTSzkx7rh1tAgB80AImw3pvLxUDdVpXbOWU+Va1GlsgP+6unjIVvqsX Sg7Bqd4QS2e6QhWXkhpEp9yM+suSmGSd9VBzu/Rkvnb0l+gERXM6Sb9HkkOg6yE9VMv7okRoeEU 8CNfuVNB78cyxUnx9+g== X-Authority-Analysis: v=2.4 cv=KItqylFo c=1 sm=1 tr=0 ts=6a16f543 cx=c_pps a=bLidbwmWQ0KltjZqbj+ezA==:117 a=bLidbwmWQ0KltjZqbj+ezA==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=uAbxVGIbfxUO_5tXvNgY:22 a=1XWaLZrsAAAA:8 a=fd4IrLrsY76uiRLARL4A:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: Fn7Ujt3L4aHkdfhwG8Bm0N_PlSinXSNW X-Proofpoint-GUID: bXlCgpG-FPO0Ns6AHjczGMQjX7BKMdQK X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.125,FMLib:17.12.100.49 definitions=2026-05-27_02,2026-05-26_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 malwarescore=0 lowpriorityscore=0 spamscore=0 priorityscore=1501 clxscore=1015 adultscore=0 suspectscore=0 bulkscore=0 impostorscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605130000 definitions=main-2605270133 On Wed, May 27, 2026 at 02:10:25PM +0200, Miguel Ojeda wrote: > On Wed, May 27, 2026 at 12:38 PM Alice Ryhl wrote: > > > > Based on some very quick research, it looks like enabling the backchain > > target feature does not affect the ABI in the sense that mixing together > > object files with and without this option will still work. If that's the > > case, we can add this to the list of known target features for this > > target in rustc, which will silence this warning. > > > > (If it affects the ABI in a breaking manner, it needs to be added as a > > separate flag rather than being added as part of the -Ctarget-feature > > flag.) > > Yes, from the different discussions what I saw is that the issue was > mixing it with `-Zpacked-struct`, but that is already rejected by the > compiler. They also discussed whether it should have been its own > flag, though. I guess you meant `-Zpacked-stack`? We need both `-Zpacked-stack`, as well as `-Ctarget-feature=+backchain`. Otherwise the result would be incorrect code, due to different stack layouts.