arm_mremap() man page

arm_mremap() man page

[Michael Kerrisk]

[Was: man pages for undocumented system calls]

Stephan,

I don't think we really need to document this system call. It has gone
away nowadays. Note also that your description below is incorrect. The
2.4 Linux source reads as follows:

        unsigned long ret = -EINVAL;

        /*
         * If we are doing a fixed mapping, and address < PAGE_SIZE,
         * then deny it.
         */
        if (flags & MREMAP_FIXED && new_addr < PAGE_SIZE &&
            vectors_base() == 0)
                goto out;

In other words, new_addr can't be less than PAGE_SIZE for MREMAP_FIXED
(if vectors_base() == 0, which I gather to mean if page 0 is being
used as a vector address page).

Also, your point in NOTES is not correct. The new_addr argument is
passed by value; it can;t be used to return anything.

Thanks,

Michael


=====
.\" This file contains the arm_mremap syscall documentation
.\"
.\" Copyright (c) 2010 Stephan Mueller <smueller-fwYZOkdEjagAvxtiuMwx3w@public.gmane.org>
.\"
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.\"
.TH ARM_MREMAP 2 2010-06-22 "Linux" "Linux Programmer's Manual"
.SH NAME
arm_mremap \- re-map a virtual memory address
.SH SYNOPSIS
.nf
.BI "size_t arm_mremap(void *" old_address ", size_t " old_size ,
.BI "             size_t " new_size ", int " flags ", void *" new_address ");
.fi
.SH DESCRIPTION
This system call is a wrapper for the
.BR mremap (2)
system call.
The difference is only that the flag
.BR MREMAP_FIXED
is disallowed compared to the standard
.BR mremap (2)
system call.

.SH NOTE
The man page for
.BR mremap (2)
defines the system call as exported by the libc. This man page
on the other hand defines the system call as exported by the kernel.
The difference is that the kernel system call returns \fInew_address\fP
as an argument whereas the libc interface returns this data as the
return code of the call. This difference however does not imply any
functional differences.

.SH "SEE ALSO"
.BR mremap (2).

.SH AUTHORS
Stephan Mueller,
.RI < smueller-fwYZOkdEjagAvxtiuMwx3w@public.gmane.org >
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Re: arm_mremap() man page

[Stephan Mueller]

Am Samstag, 9. Oktober 2010, um 07:19:34 schrieb Michael Kerrisk:

Hi Michael,

> [Was: man pages for undocumented system calls]
> 
> Stephan,
> 
> I don't think we really need to document this system call. It has gone
> away nowadays. Note also that your description below is incorrect. The
> 2.4 Linux source reads as follows:

You are right. But it exists in the kernel I am looking at: a 2.6.27 with some 
patches by a vendor.
> 
>         unsigned long ret = -EINVAL;
> 
>         /*
>          * If we are doing a fixed mapping, and address < PAGE_SIZE,
>          * then deny it.
>          */
>         if (flags & MREMAP_FIXED && new_addr < PAGE_SIZE &&
>             vectors_base() == 0)
>                 goto out;
> 
> In other words, new_addr can't be less than PAGE_SIZE for MREMAP_FIXED
> (if vectors_base() == 0, which I gather to mean if page 0 is being
> used as a vector address page).
> 
> Also, your point in NOTES is not correct. The new_addr argument is
> passed by value; it can;t be used to return anything.

Of course, sorry for the noise then. But since the syscall went away anyway, 
we can skip the man page.

Thanks
Stephan

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