On 23 September 2015 at 23:06, Dave Young <dyoung@xxxxxxxxxx> wrote:
> On 09/09/15 at 10:08am, Ard Biesheuvel wrote:
>> Version 2.5 of the UEFI spec introduces a new configuration table
>> called the 'EFI Properties table'. Currently, it is only used to
>> convey whether the Memory Protection feature is enabled, which splits
>> PE/COFF images into separate code and data memory regions.
>>
>> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
>> ---
>> drivers/firmware/efi/efi.c | 32 ++++++++++++++++++--------------
>> include/linux/efi.h | 13 +++++++++++++
>> 2 files changed, 31 insertions(+), 14 deletions(-)
>>
>> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
>> index d6144e3b97c5..5cbb8d31da33 100644
>> --- a/drivers/firmware/efi/efi.c
>> +++ b/drivers/firmware/efi/efi.c
>> @@ -26,20 +26,21 @@
>> #include <linux/platform_device.h>
>>
>> struct efi __read_mostly efi = {
>> - .mps = EFI_INVALID_TABLE_ADDR,
>> - .acpi = EFI_INVALID_TABLE_ADDR,
>> - .acpi20 = EFI_INVALID_TABLE_ADDR,
>> - .smbios = EFI_INVALID_TABLE_ADDR,
>> - .smbios3 = EFI_INVALID_TABLE_ADDR,
>> - .sal_systab = EFI_INVALID_TABLE_ADDR,
>> - .boot_info = EFI_INVALID_TABLE_ADDR,
>> - .hcdp = EFI_INVALID_TABLE_ADDR,
>> - .uga = EFI_INVALID_TABLE_ADDR,
>> - .uv_systab = EFI_INVALID_TABLE_ADDR,
>> - .fw_vendor = EFI_INVALID_TABLE_ADDR,
>> - .runtime = EFI_INVALID_TABLE_ADDR,
>> - .config_table = EFI_INVALID_TABLE_ADDR,
>> - .esrt = EFI_INVALID_TABLE_ADDR,
>> + .mps = EFI_INVALID_TABLE_ADDR,
>> + .acpi = EFI_INVALID_TABLE_ADDR,
>> + .acpi20 = EFI_INVALID_TABLE_ADDR,
>> + .smbios = EFI_INVALID_TABLE_ADDR,
>> + .smbios3 = EFI_INVALID_TABLE_ADDR,
>> + .sal_systab = EFI_INVALID_TABLE_ADDR,
>> + .boot_info = EFI_INVALID_TABLE_ADDR,
>> + .hcdp = EFI_INVALID_TABLE_ADDR,
>> + .uga = EFI_INVALID_TABLE_ADDR,
>> + .uv_systab = EFI_INVALID_TABLE_ADDR,
>> + .fw_vendor = EFI_INVALID_TABLE_ADDR,
>> + .runtime = EFI_INVALID_TABLE_ADDR,
>> + .config_table = EFI_INVALID_TABLE_ADDR,
>> + .esrt = EFI_INVALID_TABLE_ADDR,
>> + .properties_table = EFI_INVALID_TABLE_ADDR,
>> };
>> EXPORT_SYMBOL(efi);
>>
>> @@ -105,6 +106,8 @@ static ssize_t systab_show(struct kobject *kobj,
>> str += sprintf(str, "BOOTINFO=0x%lx\n", efi.boot_info);
>> if (efi.uga != EFI_INVALID_TABLE_ADDR)
>> str += sprintf(str, "UGA=0x%lx\n", efi.uga);
>> + if (efi.properties_table != EFI_INVALID_TABLE_ADDR)
>> + str += sprintf(str, "PROP=0x%lx\n", efi.properties_table);
>
> Hello, Ard and Matt
>
Hi Dave,
> I ramdomly read some of mails in linux-efi@, sorry for joining the discussion late.
>
> The sysfs file systab abuses sysfs policy about one value one file. For what we
> have done we will have to maintain it, but I think we should not add more entries
> to the file any more. Previously I thought to send a patch to add some code comment
> to avoid later patches doing such modifications, but I hesitated if I should send
> it, later I'm busy on something else..
>
While I agree that we should not be abusing this policy in the first
place, changing the semantics of 'systab' to mean 'all configuration
tables we knew about at some random point in the past' rather than
'all configuration tables passed by the firmware' is even worse imo.
Thanks,
Ard.
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