Re: [PATCH] New phys_addr() syscall

H. Peter Anvin (hpa@transmeta.com)
19 Jul 1998 07:10:30 GMT

Followup to: <199807190553.PAA00379@workaholix.atnf.CSIRO.AU>
By author: Richard.Gooch@atnf.csiro.au
In newsgroup: linux.dev.kernel
>
> Hi, all. I've implemented a simple new system call called
> phys_addr() which converts a virtual address to a physical
> address. This is useful for memory testing programmes so you can find
> out which SIMM/DIMM is causing trouble (yeah, I've got intermittent
> memory problems in one of my machines, and I want to nail the bugger).
> Sure, I know about memtest86, but it doesn't seem to find the problem,
> whereas my userspace tester does.
>
> People writing pure userspace network drivers may also find this handy
> if they want to DMA directly into userspace.
>
> I've only bothered with ix86 syscalls for now. Comments welcome. Patch
> against 2.1.109 below.
>

Question: how do you know when this is still accurate? The kernel can
change the mapping without notice, except perhaps when using mlock()
(even then?)

-hpa

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