On Fri, Jun 10, 2022 at 04:53:52PM +0800, Hui Li wrote:
> Under loongson platform, use command:
> kexec -l vmlinux... --append="root=UUID=28e1..." --initrd=...
> kexec -e
> quick restart failed like this:
>
> ********************************************************************
> [ 3.420791] VFS: Cannot open root device "UUID=6462a8a4-02fb-49..."
> [ 3.431262] Please append a correct "root=" boot option; ...
> ...
> ...
> ...
> [ 3.543175] 0801 4194304 sda1 554e69cc-01
> [ 3.543175]
> [ 3.549494] 0802 62914560 sda2 554e69cc-02
> [ 3.549495]
> [ 3.555818] 0803 8388608 sda3 554e69cc-03
> [ 3.555819]
> [ 3.562139] 0804 174553229 sda4 554e69cc-04
> [ 3.562139]
> [ 3.568463] 0b00 1048575 sr0
> [ 3.568464] driver: sr
> [ 3.574524] Kernel panic - not syncing: VFS: Unable to mount root fs...
> [ 3.582750] ---[ end Kernel panic - not syncing: VFS:...
> *******************************************************************
>
> The kernel cannot parse the UUID, the UUID is parsed in the initrd.
> For compatibility with previous platforms, loongson platform obtain
> initrd parameter through cmdline in kernel, the kernel supports use
> cmdline to parse initrd. But under the mips architecture, kexec-tools
> pass the initrd through DTB.
>
> So some modifications as follows:
>
> (1) in kexec/arch/mips/kexec-elf-mips.c
> Add patch_initrd_info(), at runtime to distinguish different cpu,
> only for loongson cpu, add initrd parameter to cmdline.
>
> (2) in kexec/arch/mips/crashdump-mips.c
> Because loongson uses a different page_offset, it should be modified
> to ensure that crashdump functionality is correct and reliable.
>
> Signed-off-by: Hui Li <lihui@xxxxxxxxxxx>
Hi Hui Li,
thanks for the follow-up and sorry for the slow response.
Overall I am happy with this approach.
I have made a few minor comments inline for your consideration.
> ---
> kexec/arch/mips/crashdump-mips.c | 3 ++
> kexec/arch/mips/kexec-elf-mips.c | 73 +++++++++++++++++++++++++++++++-
> 2 files changed, 74 insertions(+), 2 deletions(-)
>
> diff --git a/kexec/arch/mips/crashdump-mips.c b/kexec/arch/mips/crashdump-mips.c
> index aa09c83..548aeff 100644
> --- a/kexec/arch/mips/crashdump-mips.c
> +++ b/kexec/arch/mips/crashdump-mips.c
> @@ -335,6 +335,9 @@ static int patch_elf_info(void)
> /* OCTEON uses a different page_offset. */
> if (strstr(line, "Octeon"))
> elf_info64.page_offset = 0x8000000000000000ULL;
> + /* LOONGSON uses a different page_offset. */
> + else if (strstr(line, "Loongson"))
> + elf_info64.page_offset = 0xffffffff80000000ULL;
nit: 0xffffffff80000000ULL is used twice. Perhaps we could make it a #define.
And perhaps 0x8000000000000000ULL too, while we are here.
> break;
> }
> }
> diff --git a/kexec/arch/mips/kexec-elf-mips.c b/kexec/arch/mips/kexec-elf-mips.c
> index a2d11fc..b9e0341 100644
> --- a/kexec/arch/mips/kexec-elf-mips.c
> +++ b/kexec/arch/mips/kexec-elf-mips.c
> @@ -40,6 +40,74 @@ static const int probe_debug = 0;
> #define CMDLINE_PREFIX "kexec "
> static char cmdline_buf[COMMAND_LINE_SIZE] = CMDLINE_PREFIX;
>
> +/* Converts unsigned long to ascii string. */
> +static void ultoa(unsigned long i, char *str)
> +{
> + int j = 0, k;
> + char tmp;
> +
> + do {
> + str[j++] = i % 10 + '0';
> + } while ((i /= 10) > 0);
> + str[j] = '\0';
> +
> + /* Reverse the string. */
> + for (j = 0, k = strlen(str) - 1; j < k; j++, k--) {
> + tmp = str[k];
> + str[k] = str[j];
> + str[j] = tmp;
> + }
> +}
> +
> +/* Adds initrd parameters to command line. */
> +static int cmdline_add_initrd(char *cmdline, unsigned long addr, char *new_para)
> +{
> + int cmdlen, len;
> + char str[30], *ptr;
> +
> + ptr = str;
> + strcpy(str, new_para);
> + ptr += strlen(str);
> + ultoa(addr, ptr);
> + len = strlen(str);
> + cmdlen = strlen(cmdline) + len;
> + if (cmdlen > (COMMAND_LINE_SIZE - 1))
> + die("Command line overflow\n");
> + strcat(cmdline, str);
> +
> + return 0;
> +}
> +
> +/* add initrd to cmdline to compatible with previous platforms. */
> +static int patch_initrd_info(char *cmdline, unsigned long initrd_base, unsigned long initrd_size)
nit: I would prefer if the code was less than 80 columns wide.
> +{
> + const char cpuinfo[] = "/proc/cpuinfo";
> + char line[MAX_LINE];
> + FILE *fp;
> + unsigned long page_offset = PAGE_OFFSET;
> +
> + fp = fopen(cpuinfo, "r");
> + if (!fp) {
> + fprintf(stderr, "Cannot open %s: %s\n",
> + cpuinfo, strerror(errno));
> + return -1;
> + }
> + while (fgets(line, sizeof(line), fp) != 0) {
> + if (strncmp(line, "cpu model", 9) == 0) {
> + /* LOONGSON64 uses a different page_offset. */
> + if (strstr(line, "Loongson")) {
> + if (arch_options.core_header_type == CORE_TYPE_ELF64)
> + page_offset = (unsigned long)0xffffffff80000000ULL;
> + cmdline_add_initrd(cmdline, page_offset + initrd_base, " rd_start=");
> + cmdline_add_initrd(cmdline, initrd_size, " rd_size=");
> + break;
> + }
> + }
> + }
> + fclose(fp);
> + return 0;
> +}
> +
> int elf_mips_probe(const char *buf, off_t len)
> {
> struct mem_ehdr ehdr;
> @@ -171,9 +239,10 @@ int elf_mips_load(int argc, char **argv, const char *buf, off_t len,
> /* Now that the buffer for initrd is prepared, update the dtb
> * with an appropriate location */
> dtb_set_initrd(&dtb_buf, &dtb_length, initrd_base, initrd_base + initrd_size);
> - }
> -
>
> + /* Add the initrd parameters to cmdline */
> + patch_initrd_info(cmdline_buf, initrd_base, initrd_size);
> + }
> /* This is a legacy method for commandline passing used
> * currently by Octeon CPUs only */
> add_buffer(info, cmdline_buf, sizeof(cmdline_buf),
> --
> 2.20.1
>
>
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