On Thu, Oct 03, 2019 at 10:52:37AM +0200, Helge Deller wrote:
> On 03.10.19 10:14, Simon Horman wrote:
> > On Tue, Oct 01, 2019 at 05:14:16PM +0200, Helge Deller wrote:
> > > When compiling kexec-tools on a 32-bit platform, assigning an
> > > (unsigned long long) value to an (unsigned long) variable creates
> > > this warning:
> > >
> > > elf_info.c: In function 'read_phys_offset_elf_kcore':
> > > elf_info.c:805:14: warning: conversion from 'long long unsigned int' to 'long unsigned int' changes value from '18446744073709551615' to '4294967295'
> > > 805 | *phys_off = UINT64_MAX;
> > > | ^~~~~~~~~~
> > >
> > > Fix it by casting UINT64_MAX to (unsigned long) before storing it to *phys_off.
> > >
> > > Signed-off-by: Helge Deller <deller@xxxxxx>
> > >
> > > diff --git a/util_lib/elf_info.c b/util_lib/elf_info.c
> > > index 2bce5cb..4d16983 100644
> > > --- a/util_lib/elf_info.c
> > > +++ b/util_lib/elf_info.c
> > > @@ -802,7 +802,7 @@ int read_phys_offset_elf_kcore(int fd, unsigned long *phys_off)
> > > {
> > > int ret;
> > >
> > > - *phys_off = UINT64_MAX;
> > > + *phys_off = (unsigned long) UINT64_MAX;
> >
> > This seems to mask the problem that UINT64_MAX is not the right
> > initialiser for unsigned long values on 32-bit platforms.
> > Could we consider using UINT64_MAX from limits.h instead?
>
> UINT64 means it is a 64bit value, while "unsigned long" is either 32-bit,
> 64bit (or maybe in the future even 128bit?).
> Even assigning UINT32_MAX on a 32bit platform might be wrong.
> So I think the cast above is probably the best solution.
Sorry, I made a typo above.
What I meant is, can we consider using ULONG_MAX.
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