On 06/03/2019 07:56 PM, Daniel Axtens wrote:
I would just recommend putting this in sysfs. Make a new subsystem
(i.e. class) and away you go.
My hope with fwvarfs is to provide a generic place for firmware
variables so that we don't need to expand the list of firmware-specific
filesystems beyond efivarfs. I am also aiming to make things simple to
use so that people familiar with firmware don't also have to become
familiar with filesystem code in order to expose firmware variables to
userspace.
fwvarfs can also be used for variables that are not security relevant as
well. For example, with the EFI backend (patch 3), both secure and
insecure variables can be read.
I don't remember why efi variables were not put in sysfs, I think there
was some reasoning behind it originally. Perhaps look in the linux-efi
archives.
I'll have a look: I suspect the appeal of efivarfs is that it allows for
things like non-case-sensitive matching on the GUID part of the filename
while retaining case-sensitivity on the part of the filename
representing the variable name.
It seems efivars were first implemented in sysfs and then later
separated out as efivarfs.
Refer - Documentation/filesystems/efivarfs.txt.
So, the reason wasn't that sysfs should not be used for exposing
firmware variables,
but for the size limitations which seems to come from UEFI Specification.
Is this limitation valid for the new requirement of secure variables ?
Copying Matthew who can give us more insights...
Thanks & Regards,
- Nayna
