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[199.106.103.52]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-2e53ccd2564sm1592596eec.18.2026.04.17.03.37.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 17 Apr 2026 03:37:11 -0700 (PDT) Date: Fri, 17 Apr 2026 18:37:06 +0800 From: Shawn Guo To: Krzysztof Kozlowski Cc: Bjorn Andersson , Konrad Dybcio , Krzysztof Kozlowski , Dmitry Baryshkov , Arnd Bergmann , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] arm64: defconfig: Enable Qualcomm UFS and QMP UFS PHY drivers as built-in Message-ID: References: <20260417035509.1021860-1-shengchao.guo@oss.qualcomm.com> <898874b3-fb73-4a46-b440-6ea3377c2f2d@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Authority-Analysis: v=2.4 cv=d6/FDxjE c=1 sm=1 tr=0 ts=69e20d59 cx=c_pps a=cFYjgdjTJScbgFmBucgdfQ==:117 a=b9+bayejhc3NMeqCNyeLQQ==:17 a=kj9zAlcOel0A:10 a=A5OVakUREuEA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=Um2Pa8k9VHT-vaBCBUpS:22 a=FPaLsdzcxQoKVS78oFoA:9 a=CjuIK1q_8ugA:10 a=scEy_gLbYbu1JhEsrz4S:22 X-Proofpoint-GUID: Ah89rvwkA2S5oZ3Fvy9IL9vQe3CDc8ba X-Proofpoint-ORIG-GUID: Ah89rvwkA2S5oZ3Fvy9IL9vQe3CDc8ba X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDE3MDEwNiBTYWx0ZWRfX6Pr+U7rQAZQ3 LRv8CzxnzyqBI653PD663qo3bxXyiHjbdIqKoSKKGAaCm6QS4/cUbvA6VCREHl4qqpwzI6fdAZj x/RjnkAyhsc0GFPTvkGV2+awIQExmX7Bws2+Vo70FzSRW96L8FIuTAzRqqlcoh+qSLrHqBBmyzG ZKjR7t+Wo3z9RojbwSbt+SVrjaSTO1RQSMoPGjnBvrZy505U90rbft2U+KL4nMugVg5adWDzPp0 8teE9Hb8tCwsRN3T44bYnef9jtBL/xNDR+OutxpfHTAMoxuleP3e29Url/l9/Fz8NP40ztoQlIB 1kK1Ar4x5bVokBKHUTonG0VMho/bKGc036fCJXwqAOXWNaGkkojYNa9+LkwUEjJJHWjf42c4iMi egb0eM6kug8j8KjikweETkprC1MifUgidh1eh9ylGVq58cQeBaNF5nAmvDiyZu4BwDe5ft2wbEE M9WT6jZ9+T0YV8l/8ng== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-16_04,2026-04-16_03,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 phishscore=0 bulkscore=0 priorityscore=1501 malwarescore=0 lowpriorityscore=0 adultscore=0 clxscore=1015 suspectscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604170106 On Fri, Apr 17, 2026 at 10:44:20AM +0200, Krzysztof Kozlowski wrote: > On 17/04/2026 10:37, Shawn Guo wrote: > > On Fri, Apr 17, 2026 at 10:14:23AM +0200, Krzysztof Kozlowski wrote: > >> On 17/04/2026 05:55, Shawn Guo wrote: > >>> UFS is the primary storage for Linux rootfs across the breadth of > >>> Qualcomm development boards - Mobile, Automotive and IoT. With > >>> Qualcomm UFS host controller driver (SCSI_UFS_QCOM) and the UFS PHY > >>> driver (PHY_QCOM_QMP_UFS) as modules, developers need an initramfs > >> > >> Yes, you always need initramfs and every developer has it. > >> > >>> to boot from UFS, which adds friction to daily development workflows. > >> > >> No friction, it's both standard, easy and all of Qualcomm and Linaro > >> developers have it solved long time ago. > > > > I'm looking at a kernel regression by running git bisect, where kernel > > version string varies for every single boot. How do you usually deal > > with it by using initramfs? > > No difference from every other build and boot? I build kernel and the > same step I have initramfs with modules. Whether I bisect or build > kernel for normal boot is exactly the same. > > The only difference is `git bisect good`. So we have to rebuild initramfs for every single bisect. But isn't built-in make it easier and faster for the whole bisect process? It's especially useful for tasks where we do not even need to make modules, like debugging built-in drivers. > > If using initramfs is standard and easy, I wonder why Qualcomm QLI > > (meta-qcom) kernel has UFS drivers as built-in. > > This I don't know. Distros do various things, but of course there might > be an argument I do not know (e.g. like it was why distros do not make > IPV6 a module). We can consult internally, but saving use of initramfs could be part of it, I would guess. Shawn