uml: add Kernel 5.15 support via testing

Add the latest default Kernel for testing.

Signed-off-by: Christian Lamparter <[email protected]>

target/linux/uml/Makefile

@@ -14,6 +14,7 @@ BOARDNAME:=User Mode Linux
 FEATURES:=audio ext4 rootfs-part squashfs
 
 KERNEL_PATCHVER:=5.10
+KERNEL_TESTING_PATCHVER:=5.15
 
 include $(INCLUDE_DIR)/target.mk
 

target/linux/uml/README.md

@@ -28,7 +28,7 @@ console prompt. If you would like it in xterms, substitute `con=xterm` and
 `con0=xterm`. **No networking is configured** but it's a starting point. The
 resulting file system has just enough free space to start kicking the tires and
 playing in the world of 'embedded routers' along with all the resource
-restrictions that come with that world.  
+restrictions that come with that world.
 
 To configure networking and more refer to the *user mode linux* documentation
 online. A quick start goes along this line. Install the `uml-utilities`

target/linux/uml/config-5.15

@@ -0,0 +1,141 @@
+CONFIG_3_LEVEL_PGTABLES=y
+CONFIG_64BIT=y
+CONFIG_ARCH_DMA_ADDR_T_64BIT=y
+CONFIG_ARCH_EPHEMERAL_INODES=y
+CONFIG_ARCH_NO_PREEMPT=y
+CONFIG_ARCH_SUSPEND_POSSIBLE=y
+CONFIG_BLK_DEV_COW_COMMON=y
+CONFIG_BLK_DEV_LOOP=y
+CONFIG_BLK_DEV_UBD=y
+CONFIG_BLK_DEV_UBD_SYNC=y
+CONFIG_BLK_MQ_VIRTIO=y
+CONFIG_CDROM=y
+# CONFIG_COMMON_CLK is not set
+# CONFIG_COMPAT_32BIT_TIME is not set
+CONFIG_CON_CHAN="xterm"
+CONFIG_CON_ZERO_CHAN="fd:0,fd:1"
+CONFIG_CPU_SUP_AMD=y
+CONFIG_CPU_SUP_CENTAUR=y
+CONFIG_CPU_SUP_HYGON=y
+CONFIG_CPU_SUP_INTEL=y
+CONFIG_CPU_SUP_ZHAOXIN=y
+CONFIG_CRC16=y
+CONFIG_CRYPTO_BLAKE2S=y
+CONFIG_CRYPTO_CRC32=y
+CONFIG_CRYPTO_CRC32C=y
+CONFIG_CRYPTO_LIB_BLAKE2S_GENERIC=y
+CONFIG_CRYPTO_LIB_POLY1305_RSIZE=11
+CONFIG_CRYPTO_RNG2=y
+CONFIG_CRYPTO_SHA1=y
+# CONFIG_CRYPTO_TWOFISH_X86_64 is not set
+CONFIG_DEBUG_MEMORY_INIT=y
+CONFIG_DECOMPRESS_BZIP2=y
+CONFIG_DECOMPRESS_GZIP=y
+CONFIG_DNOTIFY=y
+# CONFIG_EARLY_PRINTK is not set
+CONFIG_EXT4_FS=y
+CONFIG_F2FS_FS=y
+CONFIG_FAILOVER=y
+CONFIG_FS_IOMAP=y
+CONFIG_FS_MBCACHE=y
+CONFIG_FW_LOADER_PAGED_BUF=y
+CONFIG_GENERIC_CLOCKEVENTS=y
+# CONFIG_GENERIC_CPU is not set
+CONFIG_GENERIC_CPU_DEVICES=y
+CONFIG_GENERIC_FIND_FIRST_BIT=y
+CONFIG_GENERIC_IRQ_SHOW=y
+CONFIG_HOSTFS=y
+CONFIG_HVC_DRIVER=y
+CONFIG_HW_RANDOM=y
+CONFIG_HZ_PERIODIC=y
+CONFIG_IA32_FEAT_CTL=y
+CONFIG_INITRAMFS_SOURCE=""
+CONFIG_INIT_ENV_ARG_LIMIT=128
+CONFIG_IRQ_WORK=y
+CONFIG_ISO9660_FS=y
+CONFIG_JBD2=y
+# CONFIG_JFFS2_FS is not set
+CONFIG_KALLSYMS=y
+CONFIG_KERNEL_STACK_ORDER=2
+CONFIG_LOCK_DEBUGGING_SUPPORT=y
+# CONFIG_MATOM is not set
+CONFIG_MAY_HAVE_RUNTIME_DEPS=y
+CONFIG_MCONSOLE=y
+# CONFIG_MCORE2 is not set
+CONFIG_MEMFD_CREATE=y
+CONFIG_MIGRATION=y
+CONFIG_MK8=y
+# CONFIG_MMAPPER is not set
+CONFIG_MODULES_USE_ELF_RELA=y
+# CONFIG_MPSC is not set
+CONFIG_NAMESPACES=y
+CONFIG_NEED_PER_CPU_KM=y
+CONFIG_NET_FAILOVER=y
+# CONFIG_NET_NS is not set
+CONFIG_NLS=y
+CONFIG_NO_DMA=y
+CONFIG_NO_IOMEM=y
+CONFIG_NO_IOPORT_MAP=y
+CONFIG_NR_CPUS=1
+CONFIG_NULL_CHAN=y
+# CONFIG_OF is not set
+CONFIG_PGTABLE_LEVELS=3
+CONFIG_PHYS_ADDR_T_64BIT=y
+CONFIG_PORT_CHAN=y
+CONFIG_POSIX_MQUEUE=y
+CONFIG_POSIX_MQUEUE_SYSCTL=y
+# CONFIG_PROCESSOR_SELECT is not set
+CONFIG_PROC_PAGE_MONITOR=y
+CONFIG_PTP_1588_CLOCK_OPTIONAL=y
+CONFIG_PTY_CHAN=y
+CONFIG_RD_BZIP2=y
+CONFIG_RD_GZIP=y
+CONFIG_RELAY=y
+CONFIG_SG_POOL=y
+CONFIG_SOFT_WATCHDOG=m
+CONFIG_SRCU=y
+CONFIG_SSL=y
+CONFIG_SSL_CHAN="pty"
+CONFIG_STACKTRACE=y
+CONFIG_STDERR_CONSOLE=y
+CONFIG_TICK_CPU_ACCOUNTING=y
+CONFIG_TINY_SRCU=y
+CONFIG_TTY_CHAN=y
+CONFIG_UML=y
+CONFIG_UML_NET=y
+CONFIG_UML_NET_DAEMON=y
+CONFIG_UML_NET_DETERMINISTIC_MAC=y
+CONFIG_UML_NET_ETHERTAP=y
+CONFIG_UML_NET_MCAST=y
+# CONFIG_UML_NET_PCAP is not set
+CONFIG_UML_NET_SLIP=y
+CONFIG_UML_NET_SLIRP=y
+CONFIG_UML_NET_TUNTAP=y
+# CONFIG_UML_NET_VDE is not set
+CONFIG_UML_NET_VECTOR=y
+# CONFIG_UML_PCI_OVER_VIRTIO is not set
+CONFIG_UML_RANDOM=y
+# CONFIG_UML_SOUND is not set
+CONFIG_UML_TIME_TRAVEL_SUPPORT=y
+CONFIG_UML_WATCHDOG=y
+CONFIG_UML_X86=y
+# CONFIG_USER_NS is not set
+CONFIG_VIRTIO=y
+CONFIG_VIRTIO_BLK=y
+CONFIG_VIRTIO_CONSOLE=y
+CONFIG_VIRTIO_NET=y
+CONFIG_VIRTIO_UML=y
+CONFIG_VMAP_STACK=y
+CONFIG_VM_EVENT_COUNTERS=y
+CONFIG_WATCHDOG_CORE=y
+CONFIG_X86_64=y
+CONFIG_X86_CMOV=y
+CONFIG_X86_CMPXCHG64=y
+CONFIG_X86_INTEL_USERCOPY=y
+CONFIG_X86_INTERNODE_CACHE_SHIFT=6
+CONFIG_X86_L1_CACHE_SHIFT=6
+CONFIG_X86_MINIMUM_CPU_FAMILY=64
+CONFIG_X86_TSC=y
+CONFIG_X86_USE_PPRO_CHECKSUM=y
+CONFIG_XTERM_CHAN=y
+CONFIG_ZLIB_INFLATE=y

target/linux/uml/patches-5.15/001-um-fix-default-console-kernel-parameter.patch

@@ -0,0 +1,54 @@
+From 53b5c5f559cc95fc676cb4cc9e5a8d9f0cb8f58c Mon Sep 17 00:00:00 2001
+Message-Id: <53b5c5f559cc95fc676cb4cc9e5a8d9f0cb8f58c.1659815468.git.chunkeey@gmail.com>
+From: Christian Lamparter <[email protected]>
+Date: Sat, 6 Aug 2022 21:22:01 +0200
+Subject: [PATCH v1 1/2] um: fix default console kernel parameter
+To: [email protected]
+Cc: Richard Weinberger <[email protected]>,
+    Anton Ivanov <[email protected]>,
+    Johannes Berg <[email protected]>
+
+OpenWrt's UML with 5.15 was producing odd errors/warnings during preinit
+part of the early userspace portion:
+
+|[    0.000000] Kernel command line: ubd0=root.img root=98:0 console=tty
+|[...]
+|[    0.440000] random: jshn: uninitialized urandom read (4 bytes read)
+|[    0.460000] random: jshn: uninitialized urandom read (4 bytes read)
+|/etc/preinit: line 47: can't create /dev/tty: No such device or address
+|/etc/preinit: line 48: can't create /dev/tty: No such device or address
+|/etc/preinit: line 58: can't open /dev/tty: No such device or address
+|[...] repeated many times
+
+That "/dev/tty" came from the command line (which is automatically
+added if no console= parameter was specified for the uml binary).
+
+The TLDP project tells the following about the /dev/tty:
+<https://tldp.org/HOWTO/Text-Terminal-HOWTO-7.html#ss7.3>
+| /dev/tty stands for the controlling terminal (if any) for the current
+| process.[...]
+| /dev/tty is something like a link to the actually terminal device[..]
+
+The "(if any)" is important here, since it's possible for processes to
+not have a controlling terminal.
+
+I think this was a simple typo and the author wanted tty0 there.
+
+CC: Thomas Meyer <[email protected]>
+Fixes: d7ffac33631b ("um: stdio_console: Make preferred console")
+Signed-off-by: Christian Lamparter <[email protected]>
+---
+ arch/um/kernel/um_arch.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/arch/um/kernel/um_arch.c
++++ b/arch/um/kernel/um_arch.c
+@@ -31,7 +31,7 @@
+ #include <os.h>
+ 
+ #define DEFAULT_COMMAND_LINE_ROOT "root=98:0"
+-#define DEFAULT_COMMAND_LINE_CONSOLE "console=tty"
++#define DEFAULT_COMMAND_LINE_CONSOLE "console=tty0"
+ 
+ /* Changed in add_arg and setup_arch, which run before SMP is started */
+ static char __initdata command_line[COMMAND_LINE_SIZE] = { 0 };

target/linux/uml/patches-5.15/101-mconsole-exec.patch

@@ -0,0 +1,213 @@
+#
+# Minimalist mconsole exec patch 
+#
+# 3.10 version (with bit more synchronous behavior) by fingon at iki dot fi
+# Adaptation to kernel 3.3.8 made by David Fernández (david at dit.upm.es) for 
+# Starting point: mconsole-exec-2.6.30.patch for kernel 2.6.30
+# Author of original patch: Paolo Giarrusso, aka Blaisorblade 
+#                           (http://www.user-mode-linux.org/~blaisorblade)
+#
+# Known misfeatures:
+#
+# - If output is too long, blocks (and breaks horribly) 
+# (this misfeature from 3.10 patches, when minimalizing the patch;
+#  workaround: redirect to a shared filesystem if long output is expected)
+#
+# - Nothing useful is done with stdin
+#
+--- a/arch/um/drivers/mconsole.h
++++ b/arch/um/drivers/mconsole.h
+@@ -85,6 +85,7 @@ extern void mconsole_cad(struct mc_reque
+ extern void mconsole_stop(struct mc_request *req);
+ extern void mconsole_go(struct mc_request *req);
+ extern void mconsole_log(struct mc_request *req);
++extern void mconsole_exec(struct mc_request *req);
+ extern void mconsole_proc(struct mc_request *req);
+ extern void mconsole_stack(struct mc_request *req);
+ 
+--- a/arch/um/drivers/mconsole_kern.c
++++ b/arch/um/drivers/mconsole_kern.c
+@@ -4,6 +4,7 @@
+  * Copyright (C) 2001 - 2008 Jeff Dike (jdike@{addtoit,linux.intel}.com)
+  */
+ 
++#include <linux/kmod.h>
+ #include <linux/console.h>
+ #include <linux/ctype.h>
+ #include <linux/string.h>
+@@ -27,6 +28,7 @@
+ #include <linux/mount.h>
+ #include <linux/file.h>
+ #include <linux/uaccess.h>
++#include <linux/completion.h>
+ #include <asm/switch_to.h>
+ 
+ #include <init.h>
+@@ -124,6 +126,59 @@ void mconsole_log(struct mc_request *req
+ 	mconsole_reply(req, "", 0, 0);
+ }
+ 
++void mconsole_exec(struct mc_request *req)
++{
++  struct subprocess_info *sub_info;
++  int res, len;
++  struct file *out;
++  char buf[MCONSOLE_MAX_DATA];
++
++  char *envp[] = {
++    "HOME=/", "TERM=linux",
++    "PATH=/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/sbin:/usr/local/bin",
++    NULL
++  };
++  char *argv[] = {
++    "/bin/sh", "-c",
++    req->request.data + strlen("exec "),
++    NULL
++  };
++
++  sub_info = call_usermodehelper_setup("/bin/sh", argv, envp, GFP_ATOMIC, NULL, NULL, NULL);
++  if (sub_info == NULL) {
++    mconsole_reply(req, "call_usermodehelper_setup failed", 1, 0);
++    return;
++  }
++  res = call_usermodehelper_stdoutpipe(sub_info, &out);
++  if (res < 0) {
++    kfree(sub_info);
++    mconsole_reply(req, "call_usermodehelper_stdoutpipe failed", 1, 0);
++    return;
++  }
++
++  res = call_usermodehelper_exec(sub_info, UMH_WAIT_PROC);
++  if (res < 0) {
++    kfree(sub_info);
++    mconsole_reply(req, "call_usermodehelper_exec failed", 1, 0);
++    return;
++  }
++
++  for (;;) {
++    len = out->f_op->read(out, buf, sizeof(buf), &out->f_pos);
++    if (len < 0) {
++      mconsole_reply(req, "reading output failed", 1, 0);
++      break;
++    }
++    if (len == 0)
++      break;
++    mconsole_reply_len(req, buf, len, 0, 1);
++  }
++  fput(out);
++
++  mconsole_reply_len(req, NULL, 0, 0, 0);
++}
++
++
+ void mconsole_proc(struct mc_request *req)
+ {
+ 	struct vfsmount *mnt = proc_mnt;
+@@ -190,6 +245,7 @@ void mconsole_proc(struct mc_request *re
+     stop - pause the UML; it will do nothing until it receives a 'go' \n\
+     go - continue the UML after a 'stop' \n\
+     log <string> - make UML enter <string> into the kernel log\n\
++    exec <string> - pass <string> to /bin/sh -c synchronously\n\
+     proc <file> - returns the contents of the UML's /proc/<file>\n\
+     stack <pid> - returns the stack of the specified pid\n\
+ "
+--- a/arch/um/drivers/mconsole_user.c
++++ b/arch/um/drivers/mconsole_user.c
+@@ -30,6 +30,7 @@ static struct mconsole_command commands[
+ 	{ "stop", mconsole_stop, MCONSOLE_PROC },
+ 	{ "go", mconsole_go, MCONSOLE_INTR },
+ 	{ "log", mconsole_log, MCONSOLE_INTR },
++	{ "exec", mconsole_exec, MCONSOLE_PROC },
+ 	{ "proc", mconsole_proc, MCONSOLE_PROC },
+ 	{ "stack", mconsole_stack, MCONSOLE_INTR },
+ };
+--- a/arch/um/os-Linux/file.c
++++ b/arch/um/os-Linux/file.c
+@@ -560,6 +560,8 @@ int os_create_unix_socket(const char *fi
+ 
+ 	addr.sun_family = AF_UNIX;
+ 
++	if (len > sizeof(addr.sun_path))
++		len = sizeof(addr.sun_path);
+ 	snprintf(addr.sun_path, len, "%s", file);
+ 
+ 	err = bind(sock, (struct sockaddr *) &addr, sizeof(addr));
+--- a/include/linux/kmod.h
++++ b/include/linux/kmod.h
+@@ -32,4 +32,6 @@ static inline int request_module_nowait(
+ #define try_then_request_module(x, mod...) (x)
+ #endif
+ 
++int call_usermodehelper_stdoutpipe(struct subprocess_info *sub_info, struct file **filp);
++
+ #endif /* __LINUX_KMOD_H__ */
+--- a/include/linux/umh.h
++++ b/include/linux/umh.h
+@@ -22,6 +22,7 @@ struct subprocess_info {
+ 	const char *path;
+ 	char **argv;
+ 	char **envp;
++	struct file *stdout;
+ 	int wait;
+ 	int retval;
+ 	int (*init)(struct subprocess_info *info, struct cred *new);
+--- a/kernel/umh.c
++++ b/kernel/umh.c
+@@ -28,6 +28,7 @@
+ #include <linux/async.h>
+ #include <linux/uaccess.h>
+ #include <linux/initrd.h>
++#include <linux/pipe_fs_i.h>
+ 
+ #include <trace/events/module.h>
+ 
+@@ -73,6 +74,28 @@ static int call_usermodehelper_exec_asyn
+ 	flush_signal_handlers(current, 1);
+ 	spin_unlock_irq(&current->sighand->siglock);
+ 
++	/* Install output when needed */
++	if (sub_info->stdout) {
++		struct files_struct *f = current->files;
++		struct fdtable *fdt;
++
++		sys_close(1);
++		sys_close(2);
++		get_file(sub_info->stdout);
++		fd_install(1, sub_info->stdout);
++		fd_install(2, sub_info->stdout);
++		spin_lock(&f->file_lock);
++		fdt = files_fdtable(f);
++		__set_bit(1, fdt->open_fds);
++		__clear_bit(1, fdt->close_on_exec);
++		__set_bit(2, fdt->open_fds);
++		__clear_bit(2, fdt->close_on_exec);
++		spin_unlock(&f->file_lock);
++
++		/* disallow core files */
++		current->signal->rlim[RLIMIT_CORE] = (struct rlimit){0, 0};
++	}
++
+ 	/*
+ 	 * Initial kernel threads share ther FS with init, in order to
+ 	 * get the init root directory. But we've now created a new
+@@ -332,6 +355,20 @@ static void helper_unlock(void)
+ 		wake_up(&running_helpers_waitq);
+ }
+ 
++int call_usermodehelper_stdoutpipe(struct subprocess_info *sub_info,
++					struct file **filp)
++{
++	struct file *f[2];
++
++	if (create_pipe_files(f, 0) < 0)
++		 return PTR_ERR(f);
++
++	sub_info->stdout = f[1];
++	*filp = f[0];
++	return 0;
++}
++EXPORT_SYMBOL(call_usermodehelper_stdoutpipe);
++
+ /**
+  * call_usermodehelper_setup - prepare to call a usermode helper
+  * @path: path to usermode executable

target/linux/uml/patches-5.15/102-pseudo-random-mac.patch

@@ -0,0 +1,147 @@
+===============================================================================
+
+This patch makes MAC addresses of network interfaces predictable. In
+particular, it adds a small routine that computes MAC addresses of based on
+a SHA1 hash of the virtual machine name and interface ID.
+
+TECHNICAL INFORMATION:
+
+Applies to vanilla kernel 3.9.4.
+
+===============================================================================
+--- a/arch/um/drivers/Kconfig
++++ b/arch/um/drivers/Kconfig
+@@ -146,6 +146,20 @@ config UML_NET
+ 	  enable at least one of the following transport options to actually
+ 	  make use of UML networking.
+ 
++config UML_NET_DETERMINISTIC_MAC
++	bool "Use deterministic MAC addresses for network interfaces"
++	default y
++	depends on UML_NET
++	select CRYPTO_SHA1
++	help
++        Virtual network devices inside a User-Mode Linux instance must be
++        assigned a MAC (Ethernet) address. If none is specified on the UML
++        command line, one must be automatically computed. If this option is
++        enabled, a randomly generated address is used. Otherwise, if this
++        option is disabled, the address is generated from a SHA1 hash of
++        the umid of the UML instance and the interface name. The latter choice
++        is useful to make MAC addresses predictable.
++
+ config UML_NET_ETHERTAP
+ 	bool "Ethertap transport (obsolete)"
+ 	depends on UML_NET
+--- a/arch/um/drivers/net_kern.c
++++ b/arch/um/drivers/net_kern.c
+@@ -25,6 +25,14 @@
+ #include <net_kern.h>
+ #include <net_user.h>
+ 
++#include <crypto/sha1.h>
++#include <crypto/hash.h>
++#include <linux/string.h>
++#include <linux/crypto.h>
++#include <linux/err.h>
++#include <linux/scatterlist.h>
++#include "os.h"
++
+ #define DRIVER_NAME "uml-netdev"
+ 
+ static DEFINE_SPINLOCK(opened_lock);
+@@ -274,9 +282,51 @@ static const struct ethtool_ops uml_net_
+ 	.get_ts_info	= ethtool_op_get_ts_info,
+ };
+ 
++#ifdef CONFIG_UML_NET_DETERMINISTIC_MAC
++
++/* Compute a SHA1 hash of the UML instance's id and
++ *  * an interface name. */
++static int compute_hash(const char *umid, const char *ifname, char *hash)
++{
++	struct ahash_request *desc;
++	struct crypto_ahash *tfm;
++	struct scatterlist sg;
++	char vmif[1024];
++	int ret;
++
++	strcpy (vmif, umid);
++	strcat (vmif, ifname);
++
++	tfm = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
++	if (IS_ERR(tfm))
++		return -ENOMEM;
++
++	desc = ahash_request_alloc(tfm, GFP_KERNEL);
++	if (!desc) {
++		ret = -ENOMEM;
++		goto out;
++	}
++
++	crypto_ahash_clear_flags(tfm, ~0);
++
++	sg_init_table(&sg, 1);
++	sg_set_buf(&sg, vmif, strlen(vmif));
++
++	ahash_request_set_crypt(desc, &sg, hash, strlen(vmif));
++
++	ret = crypto_ahash_digest(desc);
++out:
++	crypto_free_ahash(tfm);
++
++	return ret;
++}
++
++#endif
++
+ void uml_net_setup_etheraddr(struct net_device *dev, char *str)
+ {
+ 	unsigned char *addr = dev->dev_addr;
++	u8 hash[SHA1_DIGEST_SIZE];
+ 	char *end;
+ 	int i;
+ 
+@@ -319,9 +369,26 @@ void uml_net_setup_etheraddr(struct net_
+ 	return;
+ 
+ random:
++#ifndef CONFIG_UML_NET_DETERMINISTIC_MAC
+ 	printk(KERN_INFO
+ 	       "Choosing a random ethernet address for device %s\n", dev->name);
+ 	eth_hw_addr_random(dev);
++#else
++	printk(KERN_INFO
++	       "Computing a digest to use as ethernet address for device %s\n", dev->name);
++	if (compute_hash(get_umid(), dev->name, hash) < 0) {
++		printk(KERN_WARNING
++		       "Could not compute digest to use as ethernet address for device %s. "
++		       "Using random address instead.\n", dev->name);
++		random_ether_addr(addr);
++	}
++	else {
++		for (i=0; i < 6; i++)
++			addr[i] = (hash[i] + hash[i+6]) % 0x100;
++	}
++	addr [0] &= 0xfe; /* clear multicast bit */
++	addr [0] |= 0x02; /* set local assignment bit (IEEE802) */
++#endif
+ }
+ 
+ static DEFINE_SPINLOCK(devices_lock);
+--- a/kernel/umh.c
++++ b/kernel/umh.c
+@@ -356,12 +356,12 @@ static void helper_unlock(void)
+ }
+ 
+ int call_usermodehelper_stdoutpipe(struct subprocess_info *sub_info,
+-					struct file **filp)
++				   struct file **filp)
+ {
+ 	struct file *f[2];
+ 
+ 	if (create_pipe_files(f, 0) < 0)
+-		 return PTR_ERR(f);
++		return PTR_ERR(f);
+ 
+ 	sub_info->stdout = f[1];
+ 	*filp = f[0];

target/linux/uml/patches-5.15/104-um-increase-default-virtual-physical-memory-to-64.patch

@@ -0,0 +1,40 @@
+From d7936f11aded13f03871c0d6502d611d6a1e2dc5 Mon Sep 17 00:00:00 2001
+Message-Id: <d7936f11aded13f03871c0d6502d611d6a1e2dc5.1659815468.git.chunkeey@gmail.com>
+In-Reply-To: <53b5c5f559cc95fc676cb4cc9e5a8d9f0cb8f58c.1659815468.git.chunkeey@gmail.com>
+References: <53b5c5f559cc95fc676cb4cc9e5a8d9f0cb8f58c.1659815468.git.chunkeey@gmail.com>
+From: Christian Lamparter <[email protected]>
+Date: Sat, 6 Aug 2022 19:27:20 +0200
+Subject: [PATCH v1 2/2] um: increase default virtual physical memory to 64 MiB
+To: [email protected]
+Cc: Richard Weinberger <[email protected]>,
+    Anton Ivanov <[email protected]>,
+    Johannes Berg <[email protected]>
+
+The current 32 MiB of RAM causes OOMs to appear shortly after
+booting in a minimal OpenWrt 22.03 configuration with a
+5.10.134 kernel.
+
+Of course, passing a "mem=64M" (from the --help text) parameter
+works too, but it produces the following (info) message:
+
+| [    0.000000] Unknown kernel command line parameters "mem=64M", will be passed to user space.
+
+That's why, I think it would be nicer, if this is working out
+of the box again :).
+
+Signed-off-by: Christian Lamparter <[email protected]>
+---
+ arch/um/kernel/um_arch.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/arch/um/kernel/um_arch.c
++++ b/arch/um/kernel/um_arch.c
+@@ -130,7 +130,7 @@ static int have_root __initdata;
+ static int have_console __initdata;
+ 
+ /* Set in uml_mem_setup and modified in linux_main */
+-long long physmem_size = 32 * 1024 * 1024;
++long long physmem_size = 64 * 1024 * 1024;
+ EXPORT_SYMBOL(physmem_size);
+ 
+ static const char *usage_string =