Re: [PATCH] softmmu/physmem: Improve guest memory allocation failure error message

[Igor Mammedov]

On Fri, 20 Aug 2021 18:00:26 +0200
Philippe Mathieu-Daudé <philmd@redhat.com> wrote:

> On 8/20/21 5:53 PM, David Hildenbrand wrote:
> > On 20.08.21 17:52, Philippe Mathieu-Daudé wrote:  
> >> When Linux refuses to overcommit a seriously wild allocation we get:
> >>
> >>    $ qemu-system-i386 -m 40000000
> >>    qemu-system-i386: cannot set up guest memory 'pc.ram': Cannot
> >> allocate memory
> >>
> >> Slighly improve the error message, displaying the memory size
> >> requested (in case the user didn't expect unspecified memory size
> >> unit is in MiB):
> >>
> >>    $ qemu-system-i386 -m 40000000
> >>    qemu-system-i386: Cannot set up 38.1 TiB of guest memory 'pc.ram':
> >> Cannot allocate memory
> >>
> >> Reported-by: Bin Meng <bmeng.cn@gmail.com>
> >> Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> >> ---
> >>   softmmu/physmem.c | 4 +++-
> >>   1 file changed, 3 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/softmmu/physmem.c b/softmmu/physmem.c
> >> index 2e18947598e..2f300a9e79b 100644
> >> --- a/softmmu/physmem.c
> >> +++ b/softmmu/physmem.c
> >> @@ -1982,8 +1982,10 @@ static void ram_block_add(RAMBlock *new_block,
> >> Error **errp)
> >>                                                    
> >> &new_block->mr->align,
> >>                                                     shared, noreserve);
> >>               if (!new_block->host) {
> >> +                g_autofree char *size_s =
> >> size_to_str(new_block->max_length);
> >>                   error_setg_errno(errp, errno,
> >> -                                 "cannot set up guest memory '%s'",
> >> +                                 "Cannot set up %s of guest memory
> >> '%s'",
> >> +                                 size_s,
> >>                                    memory_region_name(new_block->mr));
> >>                   qemu_mutex_unlock_ramlist();
> >>                   return;
> >>  
> > 
> > IIRC, ram blocks might not necessarily be used for guest memory ... or
> > is my memory wrong?  
> 
> No clue, this error message was already here.

it's not only guest RAM, adding size here is marginal improvement,
(it won't help much since it's not exact match to CLI which may use suffixes 
for sizes)

> 
> No problem to change s/guest/block/ although.
>