On 20/05/26 14:58, Shivang Upadhyay wrote:
When a ppc machine is started with maxcpus greater than the number > of present CPUs (e.g., -smp cpus=2,maxcpus=8), firmware allocates >
the CPU state data buffer based on maxcpus and advertises this size > to
the kernel during fadump registration. > > However, fadump currently
fails to generate a vmcore during the > rebooted kernel because: > > 1.
The CPU state buffer length does not match what firmware > advertised
(QEMU only populates entries for present CPUs, not > maxcpus) > 2. The
kernel cannot find CPU data for all maxcpus slots
Hello Shivang, same thing from our discussion offline, can you see if this
fix belongs in the kernel instead of qemu ?
PAPR (section H.1) states:
Only CPUs that are online at the start of the Firmware Assisted Dump > will
have their register data saved.
QEMU's implementation is aligned with PAPR.
The PAPR doesn't say anything about the offline CPUs, so that may be
considered as undefined.
Let's see if it's an assumption from kernel side, and if it's possible to be
fixed there, else if we will take this patch in qemu.
Thanks,
- Aditya G
