On 1/2/2025 4:14 PM, Peter Xu wrote:
On Thu, Jan 02, 2025 at 12:34:50PM -0800, Steve Sistare wrote:
qemu_ram_alloc_from_fd allocates space if file_size == 0. If non-zero,
it uses the existing space and verifies it is large enough, but the
verification was broken when the offset parameter was introduced. As
a result, a file smaller than offset passes the verification and causes
errors later. Fix that, and update the error message to include offset.
Peter provides this concise reproducer:
$ touch ramfile
$ truncate -s 64M ramfile
$ ./qemu-system-x86_64 -object
memory-backend-file,mem-path=./ramfile,offset=128M,size=128M,id=mem1,prealloc=on
qemu-system-x86_64: qemu_prealloc_mem: preallocating memory failed: Bad
address
With the fix, the error message is:
qemu-system-x86_64: mem1 backing store size 0x4000000 is too small for
'size' option 0x8000000 plus 'offset' option 0x8000000
Can have the cc tag here too to be super clear:
Cc: qemu-sta...@nongnu.org
Done and resubmitted.
Fixes: 4b870dc4d0c0 ("hostmem-file: add offset option")
Signed-off-by: Steve Sistare <steven.sist...@oracle.com>
Reviewed-by: Peter Xu <pet...@redhat.com>
Please also feel free to attach this patch as the 1st patch when repost
cpr-transfer, it could make dependency easier no matter how this would
land.
Will do - steve
Maybe it'll be still easier to go via a migration pull that collects cpr
transfer as a whole. May depend on whether there'll be a memory API pull
before that..
