Re: [Xen-devel] xen/x86: efi: warning value truncated

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 14.06.16 at 13:19, <ross.lagerwall@xxxxxxxxxx> wrote:
> On 06/14/2016 11:50 AM, Jan Beulich wrote:
>>>>> On 14.06.16 at 12:15, <ross.lagerwall@xxxxxxxxxx> wrote:
>>> On 06/14/2016 10:24 AM, Jan Beulich wrote:
>>>>>>> On 13.06.16 at 19:13, <julien.grall@xxxxxxx> wrote:
>>>>> I noticed the warnings below when building Xen x86
>>>>> with Livepatch enabled.
>>>>
>>>> I did notice some of these too (not as many though, iirc), but I
>>>> didn't get around yet to check what exactly is causing them. Since
>>>> they're in the symbol table files only, I didn't consider them too
>>>> concerning (at worst some odd symbol won't be found or be
>>>> associated with the wrong address).
>>>>
>>>
>>> On my build, they are:
>>>
>>> multiboot1_header_start|000000000000051e|   ?  |
>>> multiboot1_header_start|00000000000008a1|   ?  |
>>> multiboot1_header_start|00000000000008a3|   ?  |
>>> multiboot1_header_start|00000000000008a8|   ?  |
>>> multiboot1_header_start|000000000000102f|   ?  |
>>> multiboot1_header_start|0000000000001033|   ?  |
>>> multiboot1_header_start|0000000000001037|   ?  |
>>> __init_end |ffff82d180650000| D |
>>
>> Aren't these symbols from the final binary (which get wrongly named
>> without fixed binutils)? Whereas Julien's issue was with warnings from
>> the assembler?
> 
> It looks the same to me. Here are the warnings:
> 
> /home/ross/src/xen/xen/.xen.efi.0s.S: Assembler messages:
> /home/ross/src/xen/xen/.xen.efi.0s.S:21: Warning: value 0x7d2f8000051e 
> truncated to 0x8000051e
> /home/ross/src/xen/xen/.xen.efi.0s.S:22: Warning: value 0x7d2f800008a1 
> truncated to 0x800008a1
> /home/ross/src/xen/xen/.xen.efi.0s.S:23: Warning: value 0x7d2f800008a3 
> truncated to 0x800008a3
> /home/ross/src/xen/xen/.xen.efi.0s.S:24: Warning: value 0x7d2f800008a8 
> truncated to 0x800008a8
> /home/ross/src/xen/xen/.xen.efi.0s.S:25: Warning: value 0x7d2f8000102f 
> truncated to 0x8000102f
> /home/ross/src/xen/xen/.xen.efi.0s.S:26: Warning: value 0x7d2f80001033 
> truncated to 0x80001033
> /home/ross/src/xen/xen/.xen.efi.0s.S:27: Warning: value 0x7d2f80001037 
> truncated to 0x80001037
> /home/ross/src/xen/xen/.xen.efi.0s.S:6741: Warning: value 0x100650000 
> truncated to 0x650000
> /home/ross/src/xen/xen/.xen.efi.1s.S: Assembler messages:
> /home/ross/src/xen/xen/.xen.efi.1s.S:21: Warning: value 0x7d2f8000051e 
> truncated to 0x8000051e
> /home/ross/src/xen/xen/.xen.efi.1s.S:22: Warning: value 0x7d2f800008a1 
> truncated to 0x800008a1
> /home/ross/src/xen/xen/.xen.efi.1s.S:23: Warning: value 0x7d2f800008a3 
> truncated to 0x800008a3
> /home/ross/src/xen/xen/.xen.efi.1s.S:24: Warning: value 0x7d2f800008a8 
> truncated to 0x800008a8
> /home/ross/src/xen/xen/.xen.efi.1s.S:25: Warning: value 0x7d2f8000102f 
> truncated to 0x8000102f
> /home/ross/src/xen/xen/.xen.efi.1s.S:26: Warning: value 0x7d2f80001033 
> truncated to 0x80001033
> /home/ross/src/xen/xen/.xen.efi.1s.S:27: Warning: value 0x7d2f80001037 
> truncated to 0x80001037
> /home/ross/src/xen/xen/.xen.efi.1s.S:6740: Warning: value 0x100650000 
> truncated to 0x650000
> 
> So, e.g. taking the last one, the assembly file contains a line:
> PTR 0xffff82d180650000 - SYMBOLS_ORIGIN
> 
> In this case SYMBOLS_ORIGIN is 0xffff82d080000000 and so it resolves to:
> .long 0x100650000
> which overflows.

Oh, right, I got confused. These are wrong because the intermediate
binary had bogus symbol table entries. So indeed these should be gone
with recent enough binutils. And I have to admit that I then have no
idea how to prevent those warnings.

Jan


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