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From: "H.J. Lu" <hjl.tools@gmail.com>
To: gnu-gabi@sourceware.org
Subject: RFC: ABI support for special memory area
Date: Sun, 01 Jan 2017 00:00:00 -0000	[thread overview]
Message-ID: <CAMe9rOrwm=U9891moSKLQEtbtLMTibFfh5Ok05YjMG_bJj7rJw@mail.gmail.com> (raw)

A system may have MCDRAM or other types of memory in addition to
normal RAM.  Here is an ABI proposal to allow placement in a section
whose sh_info field indicates the special memory type.

Any comments?

H.J.
---
To section attributes, add

#define SHF_GNU_MBIND     0x00100000

for sections used to place data or text into a special memory area.
The section names should start with ".mbind" so that they won't be
grouped together with normal sections by link editor. The sh_info
field indicates the special memory type.

To the "Program Header" section, add an inclusive range of segment types
for GNU_MBIND segments:

#define PT_GNU_MBIND_NUM    4096
#define PT_GNU_MBIND_LO     (PT_LOOS + 0x474e555)
#define PT_GNU_MBIND_HI     (PT_GNU_MBIND_LO + PT_GNU_MBIND_NUM - 1)

The array element specifies the location and size of a special memory area.
Each GNU_MBIND segment contains one GNU_MBIND section and the segment
type is PT_GNU_MBIND_LO plus the sh_info value.  If the sh_info value is
greater than PT_GNU_MBIND_NUM, no GNU_MBIND segment will be created.  Each
GNU_MBIND segment must be aligned at page boundary.  The interpretation of
the special memory area information is implementation-dependent.
Implementations may ignore GNU_MBIND segment.

Run-time support

int __gnu_mbind_setup (unsigned int type, void *addr, size_t length);

It sets up special memory area of 'type' and 'length' at 'addr' where
'addr' is a multiple of page size.  It returns zero for success, positive
value of ERRNO for non-fatal error and negative value of ERRNO for fatal
error.

After all shared objects and the executable file are loaded, relocations
are processed, for each GNU_MBIND segment in a shared object or the
executable file, run-time loader calls __gnu_mbind_setup with type,
address and length.  The default implementation of __gnu_mbind_setup is

int
__gnu_mbind_setup (unsigned int type, void *addr, size_t length)
{
  return 0;
}

which can be overridden by a different implementation at link-time.

             reply	other threads:[~2017-02-23 16:20 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-01-01  0:00 H.J. Lu [this message]
2017-01-01  0:00 ` Suprateeka R Hegde
2017-01-01  0:00   ` H.J. Lu
2017-01-01  0:00     ` Suprateeka R Hegde
2017-01-01  0:00       ` H.J. Lu
2017-01-01  0:00         ` Carlos O'Donell
2017-01-01  0:00           ` Suprateeka R Hegde
2017-01-01  0:00             ` H.J. Lu
2017-01-01  0:00               ` Suprateeka R Hegde
2017-01-01  0:00                 ` H.J. Lu
2017-01-01  0:00                   ` H.J. Lu
2017-01-01  0:00                     ` Florian Weimer
2017-01-01  0:00                       ` H.J. Lu
2017-01-01  0:00                         ` Florian Weimer
2017-01-01  0:00                           ` H.J. Lu
2017-01-01  0:00                             ` Florian Weimer
2017-01-01  0:00                               ` H.J. Lu
2017-01-01  0:00                     ` Suprateeka R Hegde
2017-01-01  0:00                       ` H.J. Lu
2017-01-01  0:00                         ` Suprateeka R Hegde
2017-01-01  0:00                           ` H.J. Lu
2017-01-01  0:00                             ` Suprateeka R Hegde
2017-01-01  0:00                               ` H.J. Lu
2017-01-01  0:00                                 ` Suprateeka R Hegde
2017-01-01  0:00                                   ` H.J. Lu
2017-01-01  0:00                                     ` Suprateeka R Hegde
2017-01-01  0:00                                       ` H.J. Lu
2017-01-01  0:00 ` Carlos O'Donell
2017-01-01  0:00   ` H.J. Lu
2017-01-01  0:00     ` Carlos O'Donell
2017-01-01  0:00       ` H.J. Lu
2017-01-01  0:00         ` Florian Weimer
2017-01-01  0:00           ` H.J. Lu

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