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

[David Hildenbrand <david@redhat.com>]

On 20.08.21 18:00, Philippe Mathieu-Daudé 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.
> 
> No problem to change s/guest/block/ although.

We should probably just adjust that as well (separate patch) ... but 
your patch subject also mentions "guest memory".

Not opposed to printing the size, although I doubt that it will really 
stop similar questions/problems getting raised.

-- 
Thanks,

David / dhildenb