Re: [Qemu-devel] [PATCH 5/7] kdump: add vmcoreinfo ELF note

[Marc-André Lureau]

Hi

On Wed, Jul 5, 2017 at 2:07 AM, Laszlo Ersek <address@hidden> wrote:
> On 06/29/17 15:23, Marc-André Lureau wrote:
>> kdump header provides offset and size of the vmcoreinfo ELF note,
>> append it if available.
>>
>> Signed-off-by: Marc-André Lureau <address@hidden>
>> ---
>>  dump.c | 48 ++++++++++++++++++++++++++++++++++++++++++++----
>>  1 file changed, 44 insertions(+), 4 deletions(-)
>>
>> diff --git a/dump.c b/dump.c
>> index 8fda5cc1ed..b78bc1fda7 100644
>> --- a/dump.c
>> +++ b/dump.c
>> @@ -788,8 +788,9 @@ static void create_header32(DumpState *s, Error **errp)
>>      uint32_t sub_hdr_size;
>>      uint32_t bitmap_blocks;
>>      uint32_t status = 0;
>> -    uint64_t offset_note;
>> +    uint64_t offset_note, offset_vmcoreinfo, size_vmcoreinfo = 0;
>>      Error *local_err = NULL;
>> +    uint8_t *vmcoreinfo = NULL;
>>
>>      /* write common header, the version of kdump-compressed format is 6th */
>>      size = sizeof(DiskDumpHeader32);
>> @@ -838,7 +839,18 @@ static void create_header32(DumpState *s, Error **errp)
>>      kh->phys_base = cpu_to_dump32(s, s->dump_info.phys_base);
>>      kh->dump_level = cpu_to_dump32(s, DUMP_LEVEL);
>>
>> -    offset_note = DISKDUMP_HEADER_BLOCKS * block_size + size;
>> +    offset_vmcoreinfo = DISKDUMP_HEADER_BLOCKS * block_size + size;
>> +    if (s->vmcoreinfo) {
>> +        uint64_t hsize, name_size;
>> +
>> +        get_note_sizes(s, s->vmcoreinfo, &hsize, &name_size, 
>> &size_vmcoreinfo);
>
> Should we round up "size_vmcoreinfo" as well? (Without the rounding,
> offset_note might become unaligned, plus I simply don't know what
> alignment is expected from kh->size_vmcoreinfo.)

In the last iteration, it only sets the kh->offset/size_vmcoreinfo. I
don't see any alignment requirement in crash.
Dave, any comment?

>
>> +        vmcoreinfo =
>> +            s->vmcoreinfo + (DIV_ROUND_UP(hsize, 4) + 
>> DIV_ROUND_UP(name_size, 4)) * 4;
>> +        kh->offset_vmcoreinfo = cpu_to_dump64(s, offset_vmcoreinfo);
>> +        kh->size_vmcoreinfo = cpu_to_dump32(s, size_vmcoreinfo);
>> +    }
>> +
>> +    offset_note = offset_vmcoreinfo + size_vmcoreinfo;
>>      kh->offset_note = cpu_to_dump64(s, offset_note);
>>      kh->note_size = cpu_to_dump32(s, s->note_size);
>>
>> @@ -848,6 +860,14 @@ static void create_header32(DumpState *s, Error **errp)
>>          goto out;
>>      }
>>
>> +    if (vmcoreinfo) {
>> +        if (write_buffer(s->fd, offset_vmcoreinfo, vmcoreinfo,
>> +                         size_vmcoreinfo) < 0) {
>> +            error_setg(errp, "dump: failed to vmcoreinfo");
>
> The verb "write" is missing from the message.
>
> Same comments for create_header64() below.
>

gone

thanks

-- 
Marc-André Lureau