* getpagesize / libsysfs broken with 0.148
@ 2004-07-15 8:51 Hannes Reinecke
2004-07-15 9:10 ` Harald Hoyer
` (4 more replies)
0 siblings, 5 replies; 6+ messages in thread
From: Hannes Reinecke @ 2004-07-15 8:51 UTC (permalink / raw)
To: linux-hotplug
[-- Attachment #1: Type: text/plain, Size: 1153 bytes --]
Hi all,
the implementation of getpagesize() is broken in klibc.
klibc uses sysinfo.mem_unit, which linux interpretes as the memory unit
all other memory values returned are to be multiplied with.
So it's perfectly ok for the linux sysinfo() to return a mem_unit of
'1', which is does if the memory available for this machine fits into
the counter.
For the unbelievers, have a look in kernel/timer.c:sys_sysinfo().
As a quick hack I've added a check for mem_unit==1 and reset the
page_size to 4096 on those cases.
Naturally, this is not the right fix. The right fix would be to get the
values from the kernel headers and/or some magic juju for those machines
with variable pagesize.
It probably would not have been noticed, but as libsysfs insists on
doing all reads from sysfs attributes with a length of pagesize, the
failures were ... interesting.
So in short, udev does _not_ work with klibc until that (or an
equivalent) patch is applied.
Cheers,
Hannes
--
Dr. Hannes Reinecke hare@suse.de
SuSE Linux AG S390 & zSeries
Maxfeldstraße 5 +49 911 74053 688
90409 Nürnberg http://www.suse.de
[-- Attachment #2: klibc-0.148-getpagesize.patch --]
[-- Type: text/x-patch, Size: 384 bytes --]
--- klibc-0.148/klibc/getpagesize.c.orig 2004-07-07 11:56:31.000000000 +0200
+++ klibc-0.148/klibc/getpagesize.c 2004-07-15 10:32:32.749143222 +0200
@@ -20,5 +20,6 @@
if ( rv == -1 )
return -1;
- return (page_size = si.mem_unit);
+ /* sysinfo returns 1 for mem_unit in some cases, so default to 4096. */
+ return (page_size = (si.mem_unit == 1 ? 4096 : si.mem_unit));
}
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: getpagesize / libsysfs broken with 0.148
2004-07-15 8:51 getpagesize / libsysfs broken with 0.148 Hannes Reinecke
@ 2004-07-15 9:10 ` Harald Hoyer
2004-07-15 9:24 ` Hannes Reinecke
` (3 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Harald Hoyer @ 2004-07-15 9:10 UTC (permalink / raw)
To: linux-hotplug
Hannes Reinecke wrote:
> Hi all,
>
> the implementation of getpagesize() is broken in klibc.
...
Hannes, care to send more patches from the Suse udev rpm upstream?
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: getpagesize / libsysfs broken with 0.148
2004-07-15 8:51 getpagesize / libsysfs broken with 0.148 Hannes Reinecke
2004-07-15 9:10 ` Harald Hoyer
@ 2004-07-15 9:24 ` Hannes Reinecke
2004-07-15 14:53 ` Daniel Stekloff
` (2 subsequent siblings)
4 siblings, 0 replies; 6+ messages in thread
From: Hannes Reinecke @ 2004-07-15 9:24 UTC (permalink / raw)
To: linux-hotplug
Harald Hoyer wrote:
> Hannes Reinecke wrote:
>
>> Hi all,
>>
>> the implementation of getpagesize() is broken in klibc.
>
> ...
>
> Hannes, care to send more patches from the Suse udev rpm upstream?
>
About to do it. Watch this space.
Cheers,
Hannes
--
Dr. Hannes Reinecke hare@suse.de
SuSE Linux AG S390 & zSeries
Maxfeldstraße 5 +49 911 74053 688
90409 Nürnberg http://www.suse.de
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: getpagesize / libsysfs broken with 0.148
2004-07-15 8:51 getpagesize / libsysfs broken with 0.148 Hannes Reinecke
2004-07-15 9:10 ` Harald Hoyer
2004-07-15 9:24 ` Hannes Reinecke
@ 2004-07-15 14:53 ` Daniel Stekloff
2004-07-15 15:57 ` [klibc] " H. Peter Anvin
2004-07-15 17:44 ` H. Peter Anvin
4 siblings, 0 replies; 6+ messages in thread
From: Daniel Stekloff @ 2004-07-15 14:53 UTC (permalink / raw)
To: linux-hotplug
On Thu, 2004-07-15 at 01:51, Hannes Reinecke wrote:
> Hi all,
>
> the implementation of getpagesize() is broken in klibc.
>
> klibc uses sysinfo.mem_unit, which linux interpretes as the memory unit
> all other memory values returned are to be multiplied with.
> So it's perfectly ok for the linux sysinfo() to return a mem_unit of
> '1', which is does if the memory available for this machine fits into
> the counter.
> For the unbelievers, have a look in kernel/timer.c:sys_sysinfo().
>
> As a quick hack I've added a check for mem_unit=1 and reset the
> page_size to 4096 on those cases.
>
> Naturally, this is not the right fix. The right fix would be to get the
> values from the kernel headers and/or some magic juju for those machines
> with variable pagesize.
>
> It probably would not have been noticed, but as libsysfs insists on
> doing all reads from sysfs attributes with a length of pagesize, the
> failures were ... interesting.
Libsysfs reads with length of pagesize because that was a sysfs
limitation. Has sysfs changed?
There use to be an ifdef klibc around the getpagesize() call but that
seems to have been removed at some point.
Thanks,
Dan
> So in short, udev does _not_ work with klibc until that (or an
> equivalent) patch is applied.
>
> Cheers,
>
> Hannes
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^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [klibc] getpagesize / libsysfs broken with 0.148
2004-07-15 8:51 getpagesize / libsysfs broken with 0.148 Hannes Reinecke
` (2 preceding siblings ...)
2004-07-15 14:53 ` Daniel Stekloff
@ 2004-07-15 15:57 ` H. Peter Anvin
2004-07-15 17:44 ` H. Peter Anvin
4 siblings, 0 replies; 6+ messages in thread
From: H. Peter Anvin @ 2004-07-15 15:57 UTC (permalink / raw)
To: linux-hotplug
Hannes Reinecke wrote:
>
> Hi all,
>
> the implementation of getpagesize() is broken in klibc.
>
> klibc uses sysinfo.mem_unit, which linux interpretes as the memory unit
> all other memory values returned are to be multiplied with.
> So it's perfectly ok for the linux sysinfo() to return a mem_unit of
> '1', which is does if the memory available for this machine fits into
> the counter.
> For the unbelievers, have a look in kernel/timer.c:sys_sysinfo().
>
> As a quick hack I've added a check for mem_unit=1 and reset the
> page_size to 4096 on those cases.
>
*SIGH* So much for the claim that there actually existed a sane way to
get the page size across platforms. This is particularly nasty because
of the definition of mmap2().
The kernel headers don't work very well since page size is a
kernel-compile-time option on some platforms, e.g. MIPS, and dynamic on
some platforms.
-hpa
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^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [klibc] getpagesize / libsysfs broken with 0.148
2004-07-15 8:51 getpagesize / libsysfs broken with 0.148 Hannes Reinecke
` (3 preceding siblings ...)
2004-07-15 15:57 ` [klibc] " H. Peter Anvin
@ 2004-07-15 17:44 ` H. Peter Anvin
4 siblings, 0 replies; 6+ messages in thread
From: H. Peter Anvin @ 2004-07-15 17:44 UTC (permalink / raw)
To: linux-hotplug
H. Peter Anvin wrote:
>
> *SIGH* So much for the claim that there actually existed a sane way to
> get the page size across platforms. This is particularly nasty because
> of the definition of mmap2().
>
> The kernel headers don't work very well since page size is a
> kernel-compile-time option on some platforms, e.g. MIPS, and dynamic on
> some platforms.
>
OK, Arjan van der Ven suggested using the AT_PAGESZ vector entry in the
ELF header; this provides a nice and uniform solution across all platforms.
-hpa
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^ permalink raw reply [flat|nested] 6+ messages in thread
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2004-07-15 8:51 getpagesize / libsysfs broken with 0.148 Hannes Reinecke
2004-07-15 9:10 ` Harald Hoyer
2004-07-15 9:24 ` Hannes Reinecke
2004-07-15 14:53 ` Daniel Stekloff
2004-07-15 15:57 ` [klibc] " H. Peter Anvin
2004-07-15 17:44 ` H. Peter Anvin
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