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Fri, 28 Aug 2026 13:57:58 +0000 (GMT) Received: from [9.87.144.188] (unknown [9.87.144.188]) by smtpav06.fra02v.mail.ibm.com (Postfix) with ESMTP; Fri, 28 Aug 2026 13:57:58 +0000 (GMT) Message-ID: Date: Fri, 28 Aug 2026 14:57:58 +0100 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 v4] s390/iomem: register initrd as an iomem resource when retain_initrd is set To: Ilya Leoshkevich , linux-s390@vger.kernel.org Cc: eoin.mcnamara@ibm.com, Christian Brauner , Alexander Graf , cathcartj08@gmail.com References: <20260818175755.3520-1-josephc@linux.ibm.com> <6f66956a-9793-4f96-b973-6e5875e5e433@linux.ibm.com> Content-Language: en-US From: Joseph Cathcart In-Reply-To: <6f66956a-9793-4f96-b973-6e5875e5e433@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Info: AW1haW4tMjYwODI4MDExNyBTYWx0ZWRfXx300RZOcaplk gSIYM3CwQHTNy3woo2iU4JKKLVhHxcwLtfvwjpp4HUiZ0sdE2o1vSxgKziyhRKLuxoEl9BGZ+ef eYYZUGMbF2dgCv0y0wZYlFvwnSC39HI= X-Proofpoint-GUID: pPQd0ogcYSrH-vPZTOodgToJEpsH5p47 X-Proofpoint-ORIG-GUID: ssfm6xT3T3C4kUdNbTZLmQknf5PAGW1g X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwODI4MDExNyBTYWx0ZWRfXyEQEj+yqe4KP n2ILE8ns6CyLyYN516GmbpamMA7TTnMn0+bF3fM9XtYDFqNDeeNrqepAzB48Do1kQrNDP9ikBq0 PRPBcHOn4daqeQYH5cZFxigSu2yFSMrItnrCjzi9vz/4vdo4DuG05cyy6SqodpBXiWIQaR2dnHn R1j3T0TiqehWgDr7chWzBytA1v9Mbi6qGi4Xr+YFfjsrTNgV2RD8eBw465pw+I/fGA63Z65+1qr DzXdL1ahD/ZbwvK/On0TaA9LgwEJm5lJSGaAnEywK4oyybC5K5BK3mwDLXlTCgLeZPleAsel9dx gQeXOV8ZL2mRLvmBIkxhhCDfqDzkOlAHZSJqS8p2XwgsxAgHXLtI8bGb6HfybSr1b0xjyrwAZqF pmIAy5vWx5DIAypad0KFjWN1zCSu1uK+78b4ksBTEM1Waw1zkux1H/Lto0a5CBqCq2ZY4fBc9Un YYBQ3jDbfYBAqoqfMcg== X-Authority-Analysis: v=2.4 cv=H7brBeYi c=1 sm=1 tr=0 ts=6a9193e9 cx=c_pps a=AfN7/Ok6k8XGzOShvHwTGQ==:117 a=AfN7/Ok6k8XGzOShvHwTGQ==:17 a=IkcTkHD0fZMA:10 a=Sv0fKeRqtYgA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=pGLkceISAAAA:8 a=gP-4D4jaNGx_qVbSGcQA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 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=2026-08-28_04,2026-08-27_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 spamscore=0 bulkscore=0 adultscore=0 priorityscore=1501 clxscore=1011 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2608280117 On 8/19/26 7:40 AM, Ilya Leoshkevich wrote: > > > On 8/18/26 19:57, Joseph Cathcart wrote: >> Currently, /proc/iomem contains no reference to initrd memory, even >> when initrd is retained and still held in RAM. This makes the memory >> ranges invisible from userspace, and unusable to programs such as >> kexec. (A sysfs bin file is created for initrd, but this doesn't >> help programs which need the explicit memory ranges) >> >> Add initrd to standard_resources[] unconditionally. Add initrd as a >> child of iomem_resources only if retain_initrd is specified. >> >> strstr() could match substrings like "retain_initrd=0" or >> "no_retain_initrd", but this is how PPC chose to check for >> "retain_initrd" param too. (arch/powerpc/kexec/ranges.c) >> >> Signed-off-by: Joseph Cathcart >> --- >>   arch/s390/kernel/setup.c | 22 ++++++++++++++++++++++ >>   1 file changed, 22 insertions(+) > > Checkpatch complains: > > $ b4 shazam > 'https://lore.kernel.org/all/20260818175755.3520-1-josephc@linux.ibm.com/' > > $ git format-patch -1 --stdout | ./scripts/checkpatch.pl - > ERROR: trailing whitespace > #58: FILE: arch/s390/kernel/setup.c:513: > +^I$ > >> diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c >> index b60284328fe3..373e54ed7519 100644 >> --- a/arch/s390/kernel/setup.c >> +++ b/arch/s390/kernel/setup.c >> @@ -481,15 +481,22 @@ static struct resource bss_resource = { >>       .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM, >>   }; >>   +static struct resource initrd_resource = { >> +    .name = "initrd", >> +    .flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM, >> +}; >> + >>   static struct resource __initdata *standard_resources[] = { >>       &code_resource, >>       &data_resource, >>       &bss_resource, >> +    &initrd_resource, >>   }; >>     static void __init setup_resources(void) >>   { >>       struct resource *res, *std_res, *sub_res; >> +    bool retain_initrd = false; >>       phys_addr_t start, end; >>       int j; >>       u64 i; >> @@ -501,6 +508,19 @@ static void __init setup_resources(void) >>       bss_resource.start = __pa_symbol(__bss_start); >>       bss_resource.end = __pa_symbol(__bss_stop) - 1; >>   +    if (IS_ENABLED(CONFIG_BLK_DEV_INITRD)) { >> +        unsigned long initrd_addr, initrd_size; >> + >> +        if (strstr(boot_command_line, "retain_initrd")) >> +            retain_initrd = true; >> +        if (retain_initrd && get_physmem_reserved(RR_INITRD, >> &initrd_addr, &initrd_size)) { >> +            initrd_resource.start = initrd_addr; >> +            initrd_resource.end = initrd_resource.start + >> initrd_size - 1; >> +        } else { >> +            retain_initrd = false; >> +        } >> +    } >> + >>       for_each_mem_range(i, &start, &end) { >>           res = memblock_alloc_or_panic(sizeof(*res), 8); >>           res->flags = IORESOURCE_BUSY | IORESOURCE_SYSTEM_RAM; >> @@ -517,6 +537,8 @@ static void __init setup_resources(void) >>             for (j = 0; j < ARRAY_SIZE(standard_resources); j++) { >>               std_res = standard_resources[j]; >> +            if (std_res == &initrd_resource && !retain_initrd) >> +                continue; >>               if (std_res->start < res->start || >>                   std_res->start > res->end) >>                   continue; > > Cc: Christian and Alexander. > > I wonder if it would make sense to move initrd resource creation to > do_populate_rootfs(), right after /sys/firmware/initrd creation, > enabling this feature on all architectures? As I will no longer have access to my IBM email address after today, I will be continuing my contributions through my personal email address "cathcartj08@gmail.com"