On 11 May 2016 at 22:31, Francois Romieu <rom...@fr.zoreil.com> wrote:
> Ard Biesheuvel <ard.biesheu...@linaro.org> :
>> The current logic around the 'use_dac' module parameter prevents the
>> r81969 driver from being loadable on 64-bit systems without any RAM
>> below 4 GB when the parameter is left at its default value.
>> So introduce a new default value -1 which indicates that 64-bit DMA
>> should be enabled implicitly, but only if setting a 32-bit DMA mask
>> has failed earlier. This should prevent any regressions like the ones
>> caused by previous attempts to change this code.
>
> I am not a huge fan but if you really need it...
>
> Which current kernel arches do exhibit the interesting
> f*ck-legacy-32-bits-only-devices property you just described ?
>
It has little to do with f*cking legacy 32-bits-only-devices if DRAM
simply starts at 0x80_0000_0000. This is on an AMD arm64 chip.
> [...]
>> diff --git a/drivers/net/ethernet/realtek/r8169.c
>> b/drivers/net/ethernet/realtek/r8169.c
>> index 94f08f1e841c..a49e8a58e539 100644
>> --- a/drivers/net/ethernet/realtek/r8169.c
>> +++ b/drivers/net/ethernet/realtek/r8169.c
> [...]
>> @@ -859,7 +859,8 @@ struct rtl8169_private {
>> MODULE_AUTHOR("Realtek and the Linux r8169 crew <netdev@vger.kernel.org>");
>> MODULE_DESCRIPTION("RealTek RTL-8169 Gigabit Ethernet driver");
>> module_param(use_dac, int, 0);
>> -MODULE_PARM_DESC(use_dac, "Enable PCI DAC. Unsafe on 32 bit PCI slot.");
>> +MODULE_PARM_DESC(use_dac,
>> + "Enable PCI DAC. Unsafe on 32 bit PCI slot (default -1: enable on
>> 64-bit archs only if needed");
>
> Nit: the parameter is bizarre enough that you could leave the original
> description.
>
OK, if you prefer. Should I send a v2?
