1 Dec
2011
1 Dec
'11
3:42 p.m.
On Thursday 01 December 2011, Catalin Marinas wrote:
Given the way register banking is done on AArch64, issuing an HVC on a 32-bit guest OS doesn't require translation on a 64-bit hypervisor. We have a similar implementation at the SVC level (for 32-bit user apps on a 64-bit kernel), the only modification was where a 32-bit SVC takes a 64-bit parameter in two separate 32-bit registers, so packing needs to be done in a syscall wrapper.
How do you deal with signed integer arguments passed into SVC or HVC from a caller? If I understand the architecture correctly, the upper halves of the argument register end up zero-padded, while the callee expects sign-extension.
Arnd