[Qemu-devel] 2 MiB alignment in qemu_vmalloc()

[Stefan Weil]

Hello Avi,

commit 36b58628 increased the alignment for some large memory
blocks (typically the system RAM) to 2 MiB (QEMU_VMALLOC_ALIGN)
on x86_64 Linux hosts.

As far as I know, this was only required for KVM.

There is a bad side effect of this increase: the Valgrind tool
only supports an alignment of up to 1 MiB. It aborts execution
with current QEMU for any target (even non-KVM targets).

It might be possible to modify Valgrind (as far as I know this
is already discussed), and of course I can also patch my local
QEMU. Nevertheless, I think the alignment should be reduced
again when there is no KVM support or KVM is disabled.
Maybe the large alignment has other unwanted side effects.

The code is in oslib-posix.c (target independent) and needs
something like kvm_enabled() (currently a macro). What would
you suggest? Maybe you can provide a patch.

Kind regards,
Stefan