? 2013?04?08? 11:53, Wang YanQing ??:
> On Mon, Apr 08, 2013 at 11:35:25AM +0800, Zhang Yanfei wrote:
>> I tried 3.8.0 kernel. Unfortunately, panicked again. For some reason, I didn't
>> see the panic message.
>>
>>> but if my memory don't lie me,
>>> I can boot v2.6.32 without a root= parameter, we had use v2.6.32 as product kernel
>>> still more than one year two years ago.
>>
>> Sigh, I tried in a real box and a kvm machine. Both panicked with no root= argument
>> message. I don't know why.
>
> It maybe your CONFIG relation problem, I guess. I have booted ok more than 3 times.
> Are your have CONFIG_BLK_DEV_INITRD=y in .config? And your cpio format initramfs
> has init script in root directory? And your init script will auto-mount your really
> device right before switch_root into it?
>
>> Anyway, Just from the code, your patch didn't fix all the possible place.
>> do_bzImage64_load may also call setup_linux_bootloader_parameters_high with
>> a null commandline. So why not change the check in
>> setup_linux_bootloader_parameters_high.
> Your are right. But your patch is wrong too.
> See below.
>
>>
>> --------------------------
>> diff --git a/kexec/arch/i386/x86-linux-setup.c b/kexec/arch/i386/x86-linux-setup.c
>> index 454fad6..6eb2e6e 100644
>> --- a/kexec/arch/i386/x86-linux-setup.c
>> +++ b/kexec/arch/i386/x86-linux-setup.c
>> @@ -116,7 +116,8 @@ void setup_linux_bootloader_parameters_high(
>> /* Fill in the command line */
>> if (cmdline_len > COMMAND_LINE_SIZE) {
>> cmdline_len = COMMAND_LINE_SIZE;
>> - }
>> + } else if (cmdline_len == 0)
>> + return;
> Can't just return, we must set the string termination guard like below:
I think this is ok for we have filled all the real_mode buffer with 0.
But I just found this fix still has problem...
Let's go through the code, take do_bzImage_load for example.
234 setup_size = kern16_size_needed + command_line_len +
235 PURGATORY_CMDLINE_SIZE;
236 real_mode = xmalloc(setup_size);
237 memset(real_mode, 0, setup_size);
......
300 setup_linux_bootloader_parameters(info, real_mode, setup_base,
301 kern16_size_needed, command_line, command_line_len,
302 initrd, initrd_len);
......
369 cmdline_end = setup_base + kern16_size_needed + command_line_len - 1;
370 elf_rel_set_symbol(&info->rhdr, "cmdline_end", &cmdline_end,
371 sizeof(unsigned long));
if no commandline and we set command_line_len to 0, line 369 is still wrong. It
will corrupt the kernel16 buf.
So your original patch is ok if we also set command_line_len to 1 and make
cmdline = "\0" in bzImage64_load.
>
> + else if (cmdline_len == 0)
> + cmdline_len = 1;
>
> If you agreed, maybe I can resend the v2 patch.
>> cmdline_ptr = ((char *)real_mode) + cmdline_offset;
>> memcpy(cmdline_ptr, cmdline, cmdline_len);
>> cmdline_ptr[cmdline_len - 1] = '\0';
>>
>
> Thanks.
>
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