diff options
| -rw-r--r-- | microkernel/mach/gnumach/interface/device/time.mdwn | 3 | ||||
| -rw-r--r-- | open_issues/clock_gettime.mdwn | 3 | ||||
| -rw-r--r-- | open_issues/gdb.mdwn | 2 | ||||
| -rw-r--r-- | open_issues/implementing_hurd_on_top_of_another_system.mdwn | 7 | ||||
| -rw-r--r-- | open_issues/vdso.mdwn | 48 | ||||
| -rw-r--r-- | system_call.mdwn | 3 |
6 files changed, 60 insertions, 6 deletions
diff --git a/microkernel/mach/gnumach/interface/device/time.mdwn b/microkernel/mach/gnumach/interface/device/time.mdwn index d399e8b5..d1e9a488 100644 --- a/microkernel/mach/gnumach/interface/device/time.mdwn +++ b/microkernel/mach/gnumach/interface/device/time.mdwn @@ -14,4 +14,5 @@ containing a `struct mapped_time_value`. See the [[reference_manual]]. Typically available as `/dev/time`, [[hurd/translator/storeio]]. Using that, [[hurd/libshouldbeinlibc]]'s `<maptime.h>` provides `maptime_map` -and `maptime_read`, see the [[hurd/reference_manual]]. +and `maptime_read`, see the [[hurd/reference_manual]]. Candidate for +replacement with [[open_issues/vDSO]] code? diff --git a/open_issues/clock_gettime.mdwn b/open_issues/clock_gettime.mdwn index 3c06c368..3caa6c28 100644 --- a/open_issues/clock_gettime.mdwn +++ b/open_issues/clock_gettime.mdwn @@ -186,3 +186,6 @@ In context of [[select]]. <braunr> do you want to make the changes yourself or should i add a new branch ? <youpi> and we'll make that a 64bit struct when we have a64bit userland + + +# Candidate for [[vDSO]] code? diff --git a/open_issues/gdb.mdwn b/open_issues/gdb.mdwn index 4782368a..6b9cd135 100644 --- a/open_issues/gdb.mdwn +++ b/open_issues/gdb.mdwn @@ -107,7 +107,7 @@ formats and more emulation vectors. * Why do we specify `-D_GNU_SOURCE`, and GNU/Linux doesn't? - * GNU/Linux: `gdb/symfile-mem.c` for vDSO. + * GNU/Linux: `gdb/symfile-mem.c` for [[vDSO]]. * GNU/Linux: `gdb/i386-nat.c` for hardware breakpoints, etc. -- we should probably use that, too. Related to Samuel's Hurd GDB patch? diff --git a/open_issues/implementing_hurd_on_top_of_another_system.mdwn b/open_issues/implementing_hurd_on_top_of_another_system.mdwn index 220c69cc..cf3db0ab 100644 --- a/open_issues/implementing_hurd_on_top_of_another_system.mdwn +++ b/open_issues/implementing_hurd_on_top_of_another_system.mdwn @@ -1,4 +1,4 @@ -[[!meta copyright="Copyright © 2010, 2011, 2012 Free Software Foundation, +[[!meta copyright="Copyright © 2010, 2011, 2012, 2013 Free Software Foundation, Inc."]] [[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable @@ -358,8 +358,9 @@ Continue reading about the [[benefits_of_a_native_Hurd_implementation]]. <peo-xaci> what you talked about above "the user space system call code is loaded as a virtual shared library" <braunr> let's call it vdso - <braunr> i have to leave in a few minutes - <braunr> keep going, i'll read later + +[[vDSO]] + <peo-xaci> thanks, I looked it up on Wikipedia and understand immediately :P <peo-xaci> so VDSOs are provided by the kernel, not a regular library file, diff --git a/open_issues/vdso.mdwn b/open_issues/vdso.mdwn new file mode 100644 index 00000000..2b2d2805 --- /dev/null +++ b/open_issues/vdso.mdwn @@ -0,0 +1,48 @@ +[[!meta copyright="Copyright © 2013 Free Software Foundation, Inc."]] + +[[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable +id="license" text="Permission is granted to copy, distribute and/or modify this +document under the terms of the GNU Free Documentation License, Version 1.2 or +any later version published by the Free Software Foundation; with no Invariant +Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license +is included in the section entitled [[GNU Free Documentation +License|/fdl]]."]]"""]] + +[[!tag open_issue_glibc open_issue_gnumach open_issue_hurd]] + +Evaluate whether or not usage of vDSOs (virtual dynamically linked shared +objects; [[!wikipedia vDSO]]) can be useful in a GNU Hurd system. + +Explanation and example for the Linux kernel: [Creating a vDSO: the Colonel's +Other +Chicken](http://www.linuxjournal.com/content/creating-vdso-colonels-other-chicken), +Matt Davis, 2012-02-06. The *Resources* given are also worth reading. +Basically, this is useful for exporting data from the kernel (generally, or +given a process context ([[Unix]]), or task/thread context, and so on). + +On a GNU Hurd system, parts of the data that makes up a process context doesn't +actually live inside the kernel, but instead is directly held in glibc. For +example `sysdeps/mach/hurd/getpid.c:__getpid` does a mere `return _hurd_pid`. +For this reason, vDSOs might not be as useful on GNU Hurd as they are with the +Linux kernel. Or, put another way, as GNU Hurd system doesn't have many +[[system_call]]s, also there aren't many that could be replaced. + +Generally only *real* [[system_call]]s should be candidates for implementation +with vDSO code, because otherwise that'd break the ([[RPC]]) system's inherent +[[/virtualization]] capabilities. + +Having vDSO code might be useful for: + + * `mach_*_self`: `mach_host_self`, `mach_task_self`, `mach_thread_self`? + + * [[mapped-time_interface|master/microkernel/mach/gnumach/interface/device/time]] + + Every application can then use that via the regular + `gettimeofday`/`clock_gettime` and similar calls instead of using the + special [[hurd/libshouldbeinlibc]]'s `<maptime.h>` interface. + + Can implement [[`clock_gettime` stuff|clock_gettime]] more easily that way, + for example for nanosecond precision? + + Now, the [[mapped-time_interface]] is virtualizable -- the question is + whether there is a way so that we can make a compromise here? diff --git a/system_call.mdwn b/system_call.mdwn index 197889cb..f180a79b 100644 --- a/system_call.mdwn +++ b/system_call.mdwn @@ -1,4 +1,4 @@ -[[!meta copyright="Copyright © 2010 Free Software Foundation, Inc."]] +[[!meta copyright="Copyright © 2010, 2013 Free Software Foundation, Inc."]] [[!meta license="""[[!toggle id="license" text="GFDL 1.2+"]][[!toggleable id="license" text="Permission is granted to copy, distribute and/or modify this @@ -14,6 +14,7 @@ kinds of functionality from the operating system kernel. A [[microkernel]]-based system typically won't offer a lot of system calls -- apart from one central one, and that is *send message* -- but instead [[RPC]]s will be used instead. +See [[GNU Mach's system calls|microkernel/mach/gnumach/interface/syscall]]. In the [[GNU Hurd|hurd]], a lot of what is traditionlly considered to be a UNIX system call is implemented (primarily by means of [[RPC]]) inside [[glibc]]. |