linux-kernel - Re: [PATCH] kexec: print out debugging message if required for kexec

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Message-ID: <C798DAB0066FD66B+590e2398-b667-40dd-abfb-99dcd728b573@uniontech.com>
Date: Thu, 30 Oct 2025 19:41:32 +0800
From: Qiang Ma <maqianga@...ontech.com>
To: Baoquan He <bhe@...hat.com>
Cc: akpm@...ux-foundation.org, kexec@...ts.infradead.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] kexec: print out debugging message if required for
 kexec_load


在 2025/10/30 17:42, Baoquan He 写道:
> On 10/30/25 at 03:33pm, Qiang Ma wrote:
>> The commit a85ee18c7900 ("kexec_file: print out debugging message
>> if required") has added general code printing in kexec_file_load(),
>> but not in kexec_load().
>>
>> Especially in the RISC-V architecture, kexec_image_info() has been
>> removed(commit eb7622d908a0 ("kexec_file, riscv: print out debugging
>> message if required")). As a result, when using '-d' for the kexec_load
>> interface, print nothing in the kernel space. This might be helpful for
>> verifying the accuracy of the data passed to the kernel. Therefore, refer to
>> this commit a85ee18c7900 ("kexec_file: print out debugging message
>> if required"), debug print information has been added.
> kexec_file_dbg_print setting when CONFIG_KEXEC_FILE is set. I doubt it
> doesn't work when you unset CONFIG_KEXEC_FILE.

Yes, I just actually tested it and it really doesn't work when unset 
CONFIG_KEXEC_FILE.

In the next version, I can add a KEXEC_DEBUG for the kernel and kexec-tools.

>> Signed-off-by: Qiang Ma <maqianga@...ontech.com>
>> ---
>>   kernel/kexec.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/kernel/kexec.c b/kernel/kexec.c
>> index 28008e3d462e..02845a7499e9 100644
>> --- a/kernel/kexec.c
>> +++ b/kernel/kexec.c
>> @@ -151,7 +151,15 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
>>   	if (ret)
>>   		goto out;
>>   
>> +	kexec_dprintk("nr_segments = %lu\n", image->nr_segments);
>>   	for (i = 0; i < nr_segments; i++) {
>> +		struct kexec_segment *ksegment;
>> +
>> +		ksegment = &image->segment[i];
>> +		kexec_dprintk("segment[%d]: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n",
>> +			      i, ksegment->buf, ksegment->bufsz, ksegment->mem,
>> +			      ksegment->memsz);
>> +
>>   		ret = kimage_load_segment(image, i);
>>   		if (ret)
>>   			goto out;
>> @@ -163,6 +171,9 @@ static int do_kexec_load(unsigned long entry, unsigned long nr_segments,
>>   	if (ret)
>>   		goto out;
>>   
>> +	kexec_dprintk("kexec_file_load: type:%u, start:0x%lx head:0x%lx flags:0x%lx\n",
>> +		      image->type, image->start, image->head, flags);
>> +
>>   	/* Install the new kernel and uninstall the old */
>>   	image = xchg(dest_image, image);
>>   
>> -- 
>> 2.20.1
>>
>>
>