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From: | Avi Kivity |
Subject: | Re: [Qemu-devel] Heads up: glibc preadv emulation breaks qemu on older kernels |
Date: | Fri, 12 Feb 2010 20:58:13 +0200 |
User-agent: | Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.7) Gecko/20100120 Fedora/3.0.1-1.fc12 Thunderbird/3.0.1 |
On 02/12/2010 07:28 PM, Anthony Liguori wrote:
On 02/12/2010 07:50 AM, Christoph Hellwig wrote:On Fri, Feb 12, 2010 at 04:49:23PM +0300, malc wrote:On Fri, 12 Feb 2010, Christoph Hellwig wrote:There are more than one way to parse the first sentence, if it should beOn Thu, Feb 11, 2010 at 07:06:08PM +0000, Richard W.M. Jones wrote:One interesting thing is that qemu has its own preadv emulation (whichAt this point the amount of bugs in the glibc preadv/pwritev code reallydoes the emulation correctly), but this is never used because qemu never gets ENOSYS back from preadv.make me want to go to use the raw system calls on Linux only. Any opinions from the maintainers if that is acceptable?read as:On linux and on linux only avoid using pread/write[v] and talk to thekernel directly. Then i agree.Yes. The BSDs tend to not play stupid emulation games in the libc, so changes of these kinds of messups to happen are far less.In all fairness, I seem to recall there being a problem with the kernel implementation of preadv/pwritev too.I think a configure option would be in order. Forever avoiding glibc is probably a bit extreme.
I'll go further and even avoid the configure options. Users should run fully updated systems.
(how would a user know whether to enable or disable the option? by the time they figure out, they might as well update the system).
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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