AMD Publishes Documentation On RDNA 1.0 ISA

[mlau]

SGDT — Store Global Descriptor Table Register

SGDT is useful only by operating-system software.

However, it can be used in application programs without causing an exception
[URL="https://www.felixcloutier.com/x86/sgdt"]https://www.felixcloutier.com/x86/sgdt

You left out the most interesting part:

[...]without causing an exception to be generated if CR4.UMIP = 0.

Does Ryzen 3xxx support UMIP? Then this can be resolved by building a kernel without UMIP support.

[shmerl]

Why [/URL]to enable something that is not useful in CPU ring lager then 0?

Apparently Wine needs it: https://lwn.net/Articles/738209/

[Peter Fodrek]

Regarding AMD, but a bit unrelated. Apparently Ryzen 3000 series CPUs have another problem besides RDRAND (RDRAND one was fixed in firmware updates). It's broken SGDT instruction:

https://github.com/ValveSoftware/Proton/issues/2927

Did AMD say anything about that?

SGDT — Store Global Descriptor Table Register

SGDT is useful only by operating-system software.

However, it can be used in application programs without causing an exception
https://www.felixcloutier.com/x86/sgdt

Why to enable something that is not useful in CPU ring lager then 0? To lower security level of the CPU or not to block not correctly written software form being executed


I know that if you block all not correctly written software your computer became software-less..

[shmerl]

Regarding AMD, but a bit unrelated. Apparently Ryzen 3000 series CPUs have another problem besides RDRAND (RDRAND one was fixed in firmware updates). It's broken SGDT instruction:

https://github.com/ValveSoftware/Proton/issues/2927

Did AMD say anything about that?

[phoronix]

Phoronix: AMD Publishes Documentation On RDNA 1.0 ISA

AMD has published their instruction set architecture documentation for their new RDNA 1.0 architecture found on their new Radeon RX 5700 series GPUs and other forthcoming products...

http://www.phoronix.com/scan.php?page=news_item&px=AMD-RDNA-1.0-ISA-Docs