Re: [PATCH 3/7] backends/hostmem: Improve error reporting when method alloc() fails

["Daniel P. Berrangé" <berrange@redhat.com>]

On Wed, Nov 11, 2026 at 01:23:38PM +0100, Markus Armbruster wrote:
> When HostMemoryBackend method alloc() fails, the error report isn't
> always clear.  E.g. "-object memory-backend-shm,id=mem0,size=1E" fails
> for me like this:
> 
>     qemu-system-x86_64: unable to map backing store for guest RAM: Cannot allocate memory
> 
> Leaves users guessing which part of the (often lengthy) command line
> needs fixing.
> 
> Let's prepend a bit of context:
> 
>     qemu-system-x86_64: can't create memory-backend-shm: unable to map backing store for guest RAM: Cannot allocate memory
> 
> This makes an error message in shm_backend_memory_alloc() partly
> redundant:
> 
>     qemu-system-x86_64: can't create memory-backend-shm: can't create shm backend with `share=off`
> 
> Change it to
> 
>     qemu-system-x86_64: can't create memory-backend-shm: backend requires 'share=on'
> 
> Signed-off-by: Markus Armbruster <armbru@redhat.com>
> ---
>  backends/hostmem-shm.c | 2 +-
>  backends/hostmem.c     | 3 +++
>  2 files changed, 4 insertions(+), 1 deletion(-)

Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>


With regards,
Daniel
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