On 10/26/2012 03:51 PM, Matt Fleming wrote:
From: Jeremy Kerr<jeremy.kerr@xxxxxxxxxxxxx> A write to an efivarfs file will not always result in a variable of 'count' size after the EFI SetVariable() call. We may have appended to the existing data (ie, with the EFI_VARIABLE_APPEND_WRITE attribute), or even have deleted the variable (with an authenticated variable update, with a zero datasize). This change re-reads the updated variable from firmware, to check for size changes and deletions. In the latter case, we need to drop the dentry.
File lingers after deletion with efivarfs_write_file. Reproduced on QEMU/OVMF, 3.8-rc vanilla kernel. Choosing the variable RTC because it's been generated by OVMF when mounting. Steps to reproduce (bash commandline): # P=/sys/firmware/efi/efivars # VAR=$P/RTC-378d7b65-8da9-4773-b6e4-a47826a833e1 # mount -t efivarfs - $P # stat -c'%s %h' $VAR 8 1 # dd if=/dev/zero of=$VAR bs=4 count=1 conv=notrunc 2>&- # stat -c'%s %h' $VAR 8 0 Writing four null bytes to $VAR should delete it. -- Lingzhu Xiang -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
