diff options
| -rw-r--r-- | Documentation/ABI/testing/sysfs-firmware-initrd | 8 | ||||
| -rw-r--r-- | Documentation/admin-guide/kernel-parameters.txt | 5 | ||||
| -rw-r--r-- | init/initramfs.c | 18 |
3 files changed, 28 insertions, 3 deletions
diff --git a/Documentation/ABI/testing/sysfs-firmware-initrd b/Documentation/ABI/testing/sysfs-firmware-initrd new file mode 100644 index 000000000000..20bf7cf77a19 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-firmware-initrd @@ -0,0 +1,8 @@ +What: /sys/firmware/initrd +Date: December 2023 +Contact: Alexander Graf <graf@amazon.com> +Description: + When the kernel was booted with an initrd and the + "retain_initrd" option is set on the kernel command + line, /sys/firmware/initrd contains the contents of the + initrd that the kernel was booted with. diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 65731b060e3f..51575cd31741 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -2438,7 +2438,7 @@ between unregistering the boot console and initializing the real console. - keepinitrd [HW,ARM] + keepinitrd [HW,ARM] See retain_initrd. kernelcore= [KNL,X86,IA-64,PPC] Format: nn[KMGTPE] | nn% | "mirror" @@ -5580,7 +5580,8 @@ Useful for devices that are detected asynchronously (e.g. USB and MMC devices). - retain_initrd [RAM] Keep initrd memory after extraction + retain_initrd [RAM] Keep initrd memory after extraction. After boot, it will + be accessible via /sys/firmware/initrd. retbleed= [X86] Control mitigation of RETBleed (Arbitrary Speculative Code Execution with Return Instructions) diff --git a/init/initramfs.c b/init/initramfs.c index 8d0fd946cdd2..76deb48c38cb 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -574,6 +574,16 @@ extern unsigned long __initramfs_size; #include <linux/initrd.h> #include <linux/kexec.h> +static ssize_t raw_read(struct file *file, struct kobject *kobj, + struct bin_attribute *attr, char *buf, + loff_t pos, size_t count) +{ + memcpy(buf, attr->private + pos, count); + return count; +} + +static BIN_ATTR(initrd, 0440, raw_read, NULL, 0); + void __init reserve_initrd_mem(void) { phys_addr_t start; @@ -715,8 +725,14 @@ done: * If the initrd region is overlapped with crashkernel reserved region, * free only memory that is not part of crashkernel region. */ - if (!do_retain_initrd && initrd_start && !kexec_free_initrd()) + if (!do_retain_initrd && initrd_start && !kexec_free_initrd()) { free_initrd_mem(initrd_start, initrd_end); + } else if (do_retain_initrd && initrd_start) { + bin_attr_initrd.size = initrd_end - initrd_start; + bin_attr_initrd.private = (void *)initrd_start; + if (sysfs_create_bin_file(firmware_kobj, &bin_attr_initrd)) + pr_err("Failed to create initrd sysfs file"); + } initrd_start = 0; initrd_end = 0; |