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

[Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>]

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.

> > None of these look particularly important to me.
> Not very important I agree with. But we should still try to eliminate
> such warnings, as they validly raise concerns to whoever gets to
> see them (and likely doesn't know they're irrelevant).
Agreed.

--
Ross Lagerwall

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel