Mahesh Jagannath Salgaonkar [off-list ref] writes:

On 05/27/2017 09:16 PM, Michal Suchanek wrote:

quoted

 - log an error message when registration fails and no error code listed
 in the switch is returned
 - translate the hv error code to posix error code and return it from
 fw_register
 - return the posix error code from fw_register to the process writing
 to sysfs
 - return EEXIST on re-registration
 - return success on deregistration when fadump is not registered
 - return ENODEV when no memory is reserved for fadump

Why do we need this ?

Because that's how we do error handling.

Userspace can always read back the fadump registration status from
/sys/kernel/fadump_registered (after echo 1 to it) to find out
whether fadump registration succeeded or not.

That's a terrible API.

If we followed that example, open() wouldn't return a value, you'd have
to do another syscall to check if it worked.

I'd appreciate if someone could test this and give me a Tested-by.

cheers