Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [Android-virt] [Embeddedxen-devel] [Xen-devel] [ANNOUNCE] Xen port to Cortex-A15 / ARMv7 with virt extensions | Date | Thu, 1 Dec 2011 15:42:19 +0000 |
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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
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