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    SubjectRe: [PATCH] New phys_addr() syscall
    Alexander Kjeldaas writes:
    > On Sun, Jul 19, 1998 at 03:53:24PM +1000, wrote:
    > > 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.
    > I this is only useful for specialized utilities, I suggest you check
    > for capable(CAP_SYS_ADMIN) in the system call.

    Sorry, I don't see the connection with capabilities. The prctl(2)
    syscall is also for specialised applications (actually, the
    LinuxThreads library). We don't need to restrict that either.
    I see no reason to restrict access to phys_addr(2). An ordinary
    (unprivileged) process can't do anything with the information other
    than print it out. A userspace network driver would indeed have
    privileges, but those relate to accessing hardware, they have nothing
    to do with translating addresses.

    Shall we also add CAP_GETPID_ALLOWED? ;-)



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