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Tue, 25 Aug 2026 09:51:47 +0000 (GMT) Received: from [9.224.77.157] (unknown [9.224.77.157]) by smtpav02.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 25 Aug 2026 09:51:47 +0000 (GMT) Message-ID: <49bc5f7c-50ff-4341-9ab7-b5a98e662b4a@linux.ibm.com> Date: Tue, 25 Aug 2026 11:51:47 +0200 Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] s390/pai: Reduce excessive debug feature size To: Heiko Carstens , Jan Polensky , Sumanth Korikkar , Alexander Gordeev , Sven Schnelle , Vasily Gorbik , Christian Borntraeger Cc: linux-s390@vger.kernel.org References: <20260825094925.1791807-1-hca@linux.ibm.com> Content-Language: en-US From: Thomas Richter Organization: IBM In-Reply-To: <20260825094925.1791807-1-hca@linux.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI1MDA4MCBTYWx0ZWRfX+4eMqZWbWeUC iBjuLgX+f0tiJ8Qmskb2s/BLL4uUV5utH15UxlNWQYzvmi4LOIk2FW6k1S7Ope5BcITrUtIO5wY 4kUyLTWCoCZWq7vuT51J4HUfsHOEXPE= X-Authority-Analysis: v=2.4 cv=AYuB2XXG c=1 sm=1 tr=0 ts=6a8d65ba cx=c_pps a=GFwsV6G8L6GxiO2Y/PsHdQ==:117 a=GFwsV6G8L6GxiO2Y/PsHdQ==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=RzCfie-kr_QcCd8fBx8p:22 a=VnNF1IyMAAAA:8 a=kDPx03Ww-hrN-jpW9KgA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 X-Proofpoint-ORIG-GUID: UG-jJCrBNP4xyEsOXQBSeyUH2TFbclcQ X-Proofpoint-GUID: UG-jJCrBNP4xyEsOXQBSeyUH2TFbclcQ X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI1MDA4MCBTYWx0ZWRfXy/D0HITds7HA R+609TRm+iwnO66avR5ZOnssRiGDpxFpUY0C45mPB32sbr3S1BtYJnXXP80+HrEz0y943q5tj62 NQwJjedL65IR9IGf9aUgFL5Hm9pKHHOSd7Fsqh+5lKT8RhI03GMjKaCJDC3FOjPu4sI7F9P7BOg CLSqq8I7QnLEP6pkl0iw7yAAg5CQy4EOqS9MzDgsvnLyD0NKxFIcMPdwKrl3YelxDq0p8guXX2K Q6sM3RqMNxQ4q/Tw8YeWPM+Wt35NXLoAJof8YR2sDrxIpAJxqHVD3MVsSnGuBpo0lrR+1+aWgrK AbNahaTlVmI9EYnLt8sAlpEf1B6EoysQNBGOMjMMH1QgiM86s8Jx39i891JQrYgpyih1nvmO6DQ BVR4L5gOBXvGM+8UYG/aOQ7VcvBjAXLuVLxbTz/19FDhtTozF1CG1IgOPDt50SdltKYJM+2ycQf ieSiF3Yh3RooBIFsBqg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-08-25_02,2026-08-24_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 phishscore=0 clxscore=1015 adultscore=0 bulkscore=0 impostorscore=0 priorityscore=1501 lowpriorityscore=0 spamscore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608250080 On 8/25/26 11:49, Heiko Carstens wrote: > The pai debug feature is registered with 256 areas, where each area > contains 32 pages. This sums up to a total of 32MiB. The code does not use > any debug exceptions, which means that 255 of those areas are never > used. In addition all existing debug feature calls have a lower level (5) > than the default level (3). > > This in turn means that without user interaction the debug feature is > unused. > > Reduce the number of areas to 1, and also reduce the number of pages for > the remaining area to 1. Since user interaction is required, the user can > also increase the size of the remaining area, instead of wasting memory by > default. > > This reduces the total size of the debug feature to 4KiB. > > Fixes: a3f8423622ef ("s390/pai_crypto: Add PAI crypto characteristics table for parameters") > Signed-off-by: Heiko Carstens > --- > arch/s390/kernel/perf_pai.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/s390/kernel/perf_pai.c b/arch/s390/kernel/perf_pai.c > index cdb8006220ca..ab76ed7ad791 100644 > --- a/arch/s390/kernel/perf_pai.c > +++ b/arch/s390/kernel/perf_pai.c > @@ -1221,7 +1221,7 @@ static int __init paipmu_setup(void) > static int __init pai_init(void) > { > /* Setup s390dbf facility */ > - paidbg = debug_register("pai", 32, 256, 128); > + paidbg = debug_register("pai", 1, 1, 128); > if (!paidbg) { > pr_err("Registration of s390dbf pai failed\n"); > return -ENOMEM; Reviewed-by: Thomas Richter -- Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany -- IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Wolfgang Wendt Geschäftsführung: David Faller Sitz der Gesellschaft: Böblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294