于 2013年04月08日 17:43, Wang YanQing 写道: > I get garbage output of /proc/cmdline and in dmesg in new > kernel context when I use kexec to load new kernel bzImage > without append command line like below: > > kexec -l bzImage --initrd=/boot/initramfs > kexec -e > > The reason is kernel copy the command line > from the bootloader like below which copy/paste > from linux/arch/x86/kernel/head_32.S: > > movl pa(boot_params) + NEW_CL_POINTER,%esi > andl %esi,%esi > jz 1f # No command line > movl $pa(boot_command_line),%edi > movl $(COMMAND_LINE_SIZE/4),%ecx > > This patch fix it. > > [ > although another patch > "kexec:i386/kexec-[bzImage|elf-x86]:x86_64/kexec-bzImage64: Use "\0" as > command line instead of empty command line" > has resolved the garbage output by put a '\0' at the start, but I thinks this > patch has sense too, it stop > kernel copy not command line data into the command line buffer in kernel
I don't think the patch is necessary, please see below. > ] > > Signed-off-by: Wang YanQing <[email protected]> > --- > Changes v1-v2: > 1:Fix the wrong cmdline_end's value > kexec/arch/i386/kexec-bzImage.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/kexec/arch/i386/kexec-bzImage.c b/kexec/arch/i386/kexec-bzImage.c > index 29f280d..2954f92 100644 > --- a/kexec/arch/i386/kexec-bzImage.c > +++ b/kexec/arch/i386/kexec-bzImage.c > @@ -119,6 +119,7 @@ int do_bzImage_load(struct kexec_info *info, > unsigned long cmdline_end; > unsigned long kern16_size_needed; > unsigned long heap_size = 0; > + off_t alloc_command_line_len = 0; > > /* > * Find out about the file I am about to load. > @@ -145,10 +146,12 @@ int do_bzImage_load(struct kexec_info *info, > dbgprintf("Kernel command line too long for kernel!\n"); > return -1; > } > + alloc_command_line_len = (uintmax_t)setup_header.cmdline_size; > } else { > if (command_line_len > 255) { > dbgprintf("WARNING: This kernel may only support 255 > byte command lines\n"); > } > + alloc_command_line_len = 255; > } > > if (setup_header.protocol_version >= 0x0205) { > @@ -231,7 +234,7 @@ int do_bzImage_load(struct kexec_info *info, > if (kern16_size_needed < 4096) > kern16_size_needed = 4096; > } > - setup_size = kern16_size_needed + command_line_len + > + setup_size = kern16_size_needed + alloc_command_line_len + > PURGATORY_CMDLINE_SIZE; > real_mode = xmalloc(setup_size); > memset(real_mode, 0, setup_size); > @@ -366,7 +369,7 @@ int do_bzImage_load(struct kexec_info *info, > ®s16, sizeof(regs16)); > } > elf_rel_set_symbol(&info->rhdr, "entry32_regs", ®s32, > sizeof(regs32)); > - cmdline_end = setup_base + kern16_size_needed + command_line_len - 1; > + cmdline_end = setup_base + kern16_size_needed + alloc_command_line_len > - 1; This is obviously wrong. Purgatory may append a kexec_jump_back_entry= argument into the commandline. It is an argument belongs to the commandline. So why there is a buf filled with 0 (alloc_command_line_len) before it in the commandline buf. > elf_rel_set_symbol(&info->rhdr, "cmdline_end", &cmdline_end, > sizeof(unsigned long)); > _______________________________________________ kexec mailing list [email protected] http://lists.infradead.org/mailman/listinfo/kexec
