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Complete the kernel bootstrap by adding kexec of Linux from Fiwix.

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A tiny bootloader bootstrap has been added to compile the builder-hex0 kernel from hex0 source.
The boot compiler is builder-hex0-x86-stage1.hex0 and builder-hex0-x86-stage1.bin.
The builder-hex0 kernel is now named builder-hex0-x86-stage2.hex0.
The inclusion of a binary seed resolves the problem with the previous strategy which used an
architecture-specific hex0 compiler.

If sysb detects a full disk (i.e. DISK=sda) it now partitions the disk unconditionally because
previously fdisk was reporting existing but empty partitions which resulted in no
parititions being created.

e2fsprogs is now built with --disable-tls because musl was built on Fiwix without full threading
support and mkfs.ext4 was crashing without disabling thread local storage.

kexec-linux writes the linux kernel and initramfs to a RAM drive on Fiwix which ensure
a pre-allocated contiguous memory block. The following is written to the ram drive:
a 32-bit number which is the size of the kernel in bytes, a 32-bit number which is the size
of the initramfs in bytes, followed by the Linux kernel image, followed by the initramfs.

kexec-fiwix invokes a sync syscall to ensure all writes are flushed to
the ram drive and then initiates the kexec by shutting down Fiwix with a reboot syscall.
Fiwix knows whether and how to perform the kexec based on kernel parameters passed to it.
This commit is contained in:
rick-masters 2023-05-10 14:33:42 +00:00
parent e86db47b6e
commit a2fcf1ced9
23 changed files with 633 additions and 277 deletions
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91
sysa/kexec-linux/src/kexec-linux.c Normal file
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/* SPDX-FileCopyrightText: 2023 Richard Masters <grick23@gmail.com> */
/* SPDX-License-Identifier: MIT */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <time.h>
int append_file(FILE *dst_file, char *src_file_name);
int main(int argc, char **argv) {
char *ramdrive_file_name, *kernel_file_name, *initramfs_file_name;
FILE *ramdrive_file;
struct stat stats;
if (argc < 3) {
puts("Usage: fiwix-kexec-linux <ram-drive-name> <kernel-file-name> <initramfs-file-name>");
exit(1);
}
ramdrive_file_name = argv[1];
kernel_file_name = argv[2];
initramfs_file_name = argv[3];
ramdrive_file = fopen(ramdrive_file_name, "wb");
/* Write length of kernel */
if (stat(kernel_file_name, &stats) == 0) {
fwrite(&stats.st_size, sizeof(stats.st_size), 1, ramdrive_file);
} else {
fprintf(stderr, "Cannot stat kernel file '%s'\n", kernel_file_name);
exit(1);
}
/* Write length of initramfs */
if (stat(initramfs_file_name, &stats) == 0) {
fwrite(&stats.st_size, sizeof(stats.st_size), 1, ramdrive_file);
} else {
fprintf(stderr, "Cannot stat initramfs file '%s'\n", initramfs_file_name);
exit(1);
}
if (append_file(ramdrive_file, kernel_file_name)) {
fprintf(stderr, "Cannot append kernel '%s'\n", kernel_file_name);
exit(1);
}
if (append_file(ramdrive_file, initramfs_file_name)) {
fprintf(stderr, "Cannot append initramfs '%s'\n", initramfs_file_name);
exit(1);
}
fclose(ramdrive_file);
/* Perform syscall sync */
__asm__ __volatile__(
"movl $0x00000024, %%eax\n\t"
"int $0x80\n\t"
: /* no output */
: /* no input */
);
/* Perform syscall reboot to initiate kexec */
__asm__ __volatile__(
"movl $0x58, %%eax\n\t"
"movl $0xfee1dead, %%ebx\n\t"
"movl $0x28121969, %%ecx\n\t"
"movl $0xcdef0123, %%edx\n\t"
"movl $0x00, %%esi\n\t"
"int $0x80\n\t"
: /* no output */
: /* no input */
);
}
int append_file(FILE *dst_file, char *src_file_name) {
FILE *src_file;
char buff[BUFSIZ];
size_t n;
if (src_file = fopen(src_file_name, "rb")) {
while ((n = fread(buff, 1, BUFSIZ, src_file)) != 0) {
fwrite(buff, 1, n, dst_file );
}
fclose(src_file);
return 0;
} else {
printf("Cannot open file '%s'\n", src_file_name);
return 1;
}
}