[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Qemu-devel] [PATCH 2/7] QEMU does not currently support host pages

From: Richard Henderson
Subject: Re: [Qemu-devel] [PATCH 2/7] QEMU does not currently support host pages that are larger than guest pages, likely due to glibc using fixed mmap requests.
Date: Tue, 21 Jun 2016 17:55:51 -0700
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1

On 06/20/2016 06:25 AM, Peter Maydell wrote:
On 19 June 2016 at 19:24, Richard Henderson <address@hidden> wrote:
On 06/19/2016 02:46 AM, Peter Maydell wrote:
This is supposed to work -- for instance the linux-user/mmap.c
code has support for host pages and target pages not being the same.
In particular for ARM guests TARGET_PAGE_SIZE is 1K but the
host page size is 4K, so the config of "host page larger than
guest" isn't untested.

You're right, it isn't untested, it's completely broken.


Is there a way we can warn about this which doesn't give
unnecessary warnings for:
 (a) the ARM case
 (b) things which don't actually care (I'm thinking the
     gcc test suite and similar stuff which doesn't actually
     mess with mmap in practice)

Not that I'm aware of.

What's worse is that even the gcc testsuite winds up caring, because the guest binary can't even be mapped, much less run far enough to get to a mmap syscall. See e.g. that aarch64 64k example, and look at our standard linux-user-0.3 tests.


reply via email to

[Prev in Thread] Current Thread [Next in Thread]