[RFC] efi: variable name size limit in efivar_init()

[Heinrich Schuchardt <xypron.glpk@xxxxxx>]

Hello Ard,

in efivar_init() I read:

        /*
         * Per EFI spec, the maximum storage allocated for both
         * the variable name and variable data is 1024 bytes.
         */

        do {
                variable_name_size = 1024;

This dates back at least to Linux 2.5.0 of 23-Nov-2001 where in
arch/ia64/kernel/efivars.c we have:

/*
 * The maximum size of VariableName + Data = 1024
 * Therefore, it's reasonable to save that much
 * space in each part of the structure,
 * and we use a page for reading/writing.
 */

I cannot find this 1024 byte size limit neither in UEFI spec 2.8B nor in
EFI spec 1.1.

Variable d719b2cb-3d3a-4596-a3bc-dad00e67656f-db has 5080 bytes of data
on my laptop.

It may not reasonable to use a variable name exceeding 512 UTF-16
characters. But shouldn't we handle this case gracefully in efivar_init()?

Best regards

Heinrich