efivar fails to read variables

The problem is due to the kernel not supporting the deprecated statfs() call on the efivarfs file system.

To demonstrate this I have created the following program (statfs.c):

#include <sys/vfs.h>
#include <stdio.h>

int main(int argc, char *argv[])
{
        struct statfs s;
        int ret;

        if (argc < 2) {
                printf("usage: %s <dirpath>\n", argv[0]);
                return 1;
        }

        ret = statfs(argv[1], &s);
        if (ret == -1) {
                perror("statfs");
                return 1;
        } else {
                printf("%s type: 0x%llx\n", argv[1],
                       (unsigned long long)s.f_type);
        }
        return 0;
}

When I run it I get the following output:

$ ./statfs /sys/firmware/efi
/sys/firmware/efi type: 0x62656572
$ ./statfs /sys/firmware/efi/efivars/
statfs: Invalid argument
$ mount | grep efivarfs
efivarfs on /sys/firmware/efi/efivars type efivarfs (ro,nosuid,nodev,noexec,relatime)

Though efivarfs is mounted on /sys/firmware/efi/efivars the statfs call fails.

Kernel commit d86ff3333cb1 ("efivarfs: expose used and total size") introduced an EFI runtime call QueryVariableInfo().

In U-Boot's EFI_RT_PROPERTIES_TABLE_VERSION the flag EFI_RT_SUPPORTED_QUERY_VARIABLE_INFO is not set.

U-Boot currently does not implement QueryVariableInfo at runtime. This function is not needed for a read only efivarfs. I think it would be more appropriate to check if GetVariable is enabled in efi.runtime_supported_mask.

Patch sent upstream https://lore<email address hidden>/T/#u

Without this patch the Ubuntu installer on systems using U-Boot (e.g. riscv64) will fail.

With kernel 6.5.0-6-generic #6.1-Ubuntu SMP Thu Sep 21 12:51:18 from ppa:esmil/ppa efivar works fine.