summaryrefslogtreecommitdiff
path: root/open_issues/glibc_tls_segment_tcbhead_t_dtv_offset.mdwn
blob: 47f104c6cc0ddc25a394caaf382093a665e06553 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
[[!meta copyright="Copyright © 2010 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]]

IRC, unknown channel, unknown date.

    <youpi> you can hardcode DTV_OFFSET as 4 for now
    <youpi> it's the offset of the dtv field in the tcbhead_t structure from hurd/libpthread
    <tschwinge> youpi: May very well be that I'm misunderstanding something, but wouldn't it rather be the offset of tcb in __pthread + the offset of dtv in tcbhead_t (which indeed is 4)?
    <youpi> what you don't know is that DTV_OFFSET is not relative to __pthread, but to the tls segment
    <tschwinge> Oh, aha.  Thanks.
    <youpi> and drepper abused the fact that in nptl __pthread appears at the start of the tls segment

kFreeBSD, glibc:

    ++#if 0
    + DTV_OFFSET                    offsetof(struct pthread, header.dtv)
    ++#else
    ++DTV_OFFSET                      offsetof(struct _pthread_descr_struct, p_header.data.dtvp)
    ++#endif