Hi Mike,
On Fri, Jan 3, 2014 at 1:29 AM, Mike Frysinger <vapier@xxxxxxxxxx> wrote:
> On Wednesday 01 January 2014 14:56:15 Michael Kerrisk (man-pages) wrote:
>> .SH DESCRIPTION
>> The "vDSO" is a small shared library that
>> the kernel automatically maps into the
>> address space of all user-space applications.
>> Applications usually do not need to concern themselves with these details
>> as the vDSO is most commonly called by the C library.
>> This way you can code in the normal way using standard functions
>> and the C library will take care
>> of using any functionality that is available via the vDSO.
>
> seems like sentences in this new version are excessively wrapped. for
> example, this first one will easily fit into two lines. is this just due to the
> editing process ? content changed but things weren't re-wrapped ? or do you
> not wrap to 80 cols ? (this is beyond the rule of "wrap to commas and
> periods").
I prefer wrapping to about 75 columns or less. (I document this in
man-pages(7), but perhaps that's not prominently enough.) Reduces the
chances of wrapping problems with patches in some mailers. (And I may
have been overenthusiastic in wrapping lines that were close to 75
chars.)
>> There are some system calls the kernel provides that
>> user space code ends up using frequently,
>
> shouldn't this be "user-space" now ?
Yep.
>> .SH ARCHITECTURE_SPECIFIC NOTES
>
> change the _ to a space ?
Typo. Should have been "-"
>> The subsections below provide architecture-specific notes
>> on the vDSO.
>
> another example of a sentence easily fitting on one line (there are many)
>
>> Note that the vDSO that is used is based on the ABI of your user-space code
>> and not the ABI of the kernel.
>> Thus, for example,
>> when you run an i386 32-bit ELF binary,
>> you'll get the same vDSO regardless of whether you run it under
>> an i386 32-bit kernel or under an x86_64 64-bit kernel.
>> Thus, the name of the user-space ABI should be used to determine
>> which of the sections below is relevant.
>
> having two sentences in a row start with "Thus" is a little funny sounding.
> could change one to "So" and largely be the same.
Thanks. Fixed now.
>> The system calls listed here have the same semantics as if you called them
>> directly via
>> .BR syscall (2),
>> so refer to the relevant
>> documentation for each.
>> The table below lists the functions available via this mechanism.
>> .if t \{\
>> .ft CW
>> \}
>> .TS
>> l.
>> function
>> _
>> clock_gettime
>> getcpu
>> getpid
>> getppid
>> gettimeofday
>> set_tid_address
>> .TE
>> .if t \{\
>> .in
>> .ft P
>> \}
>
> my troff foo is not strong. this section renders funny for me -- there's three
> blank lines above the table. do you see the same thing ?
Strange. I don't.
> The Itanium port is somewhat tricky. In addition to the vDSO above, it
> also has "light-weight system calls" (also known as "fast syscalls" or
> "fsys"). You can invoke these via the __kernel_syscall_via_epc vDSO
> helper. The system calls listed here have the same semantics as if you
> called them directly via syscall(2), so refer to the relevant
> documentation for each. The table below lists the functions available
> via this mechanism.
>
>
>
> function
> ────────────────
> clock_gettime
> getcpu
>
>> .SS parisc (hppa) functions
>> .\" See linux/arch/parisc/kernel/syscall.S
>> .\" See linux/Documentation/parisc/registers
>> The parisc port has a code page full of utility functions
>> called a gateway page.
>> Rather than use the normal ELF auxiliary vector approach,
>> it passes the address of
>> the page to the process via the SR2 register.
>> The permissions on the page are such that merely executing those addresses
>> automatically executes with kernel privileges and not in user-space.
>
> should be "user space" i think.
Yup.
Thanks for checking the page, Mike.
Cheers,
Michael
--
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/
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