From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: Linus Walleij <linus.walleij@linaro.org>,
Christoph Hellwig <hch@lst.de>,
Alexander Viro <viro@zeniv.linux.org.uk>,
"linux-kernel@vger.kernel.org" <kernel@vger.kernel.org>,
linux-arch <linux-arch@vger.kernel.org>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Oleg Nesterov <oleg@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 4/9] ARM: syscall: always store thread_info->syscall
Date: Mon, 28 Sep 2020 16:08:43 +0100 [thread overview]
Message-ID: <20200928150843.GB1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <CAK8P3a0BZ-zdk+RB5ODcVs2z-Y6xmLCp57uzivUGWRcoeH2fQQ@mail.gmail.com>
On Mon, Sep 28, 2020 at 02:42:43PM +0200, Arnd Bergmann wrote:
> > I need some idea how this numberspace is managed in order to
> > understand the code so I can review it, I guess it all makes perfect
> > sense but I need some background here.
>
> I also had never understood this part before, and I'm still not
> sure where the 0x900000 actually comes from, though my best
> guess is that this was intended as a an OS specific number space,
> with '9' being assigned to Linux (similar to the way Itanium and
> MIPS do with their respective offsets). By the time EABI got added,
> this was apparently no longer considered helpful.
It is an OS specific number space, originally designed to allow
RISC OS programs to be run under Linux. There was indeed such a
project, but that died and the code ripped out. EABI, by using
SWI 0 - or more accurately, not reading the SWI opcode, trampled
over the ability for RISC OS programs to be run under Linux.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
WARNING: multiple messages have this Message-ID (diff)
From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Arnd Bergmann <arnd@arndb.de>
Cc: linux-arch <linux-arch@vger.kernel.org>,
Linus Walleij <linus.walleij@linaro.org>,
"linux-kernel@vger.kernel.org" <kernel@vger.kernel.org>,
Oleg Nesterov <oleg@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christoph Hellwig <hch@lst.de>,
Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 4/9] ARM: syscall: always store thread_info->syscall
Date: Mon, 28 Sep 2020 16:08:43 +0100 [thread overview]
Message-ID: <20200928150843.GB1551@shell.armlinux.org.uk> (raw)
In-Reply-To: <CAK8P3a0BZ-zdk+RB5ODcVs2z-Y6xmLCp57uzivUGWRcoeH2fQQ@mail.gmail.com>
On Mon, Sep 28, 2020 at 02:42:43PM +0200, Arnd Bergmann wrote:
> > I need some idea how this numberspace is managed in order to
> > understand the code so I can review it, I guess it all makes perfect
> > sense but I need some background here.
>
> I also had never understood this part before, and I'm still not
> sure where the 0x900000 actually comes from, though my best
> guess is that this was intended as a an OS specific number space,
> with '9' being assigned to Linux (similar to the way Itanium and
> MIPS do with their respective offsets). By the time EABI got added,
> this was apparently no longer considered helpful.
It is an OS specific number space, originally designed to allow
RISC OS programs to be run under Linux. There was indeed such a
project, but that died and the code ripped out. EABI, by using
SWI 0 - or more accurately, not reading the SWI opcode, trampled
over the ability for RISC OS programs to be run under Linux.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
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linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-09-28 15:08 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-07 15:36 [PATCH 0/9] ARM: remove set_fs callers and implementation Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-07 15:36 ` [PATCH 1/9] mm/maccess: fix unaligned copy_{from,to}_kernel_nofault Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-08 6:11 ` Christoph Hellwig
2020-09-08 6:11 ` Christoph Hellwig
2020-09-27 9:25 ` Linus Walleij
2020-09-27 9:25 ` [PATCH 1/9] mm/maccess: fix unaligned copy_{from, to}_kernel_nofault Linus Walleij
2020-09-07 15:36 ` [PATCH 2/9] ARM: traps: use get_kernel_nofault instead of set_fs() Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-08 6:15 ` Christoph Hellwig
2020-09-08 6:15 ` Christoph Hellwig
2020-09-17 17:29 ` Arnd Bergmann
2020-09-17 17:29 ` Arnd Bergmann
2020-09-18 7:42 ` Russell King - ARM Linux admin
2020-09-18 7:42 ` Russell King - ARM Linux admin
2020-09-18 12:36 ` Arnd Bergmann
2020-09-18 12:36 ` Arnd Bergmann
2020-09-07 15:36 ` [PATCH 3/9] ARM: oabi-compat: add epoll_pwait handler Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-08 6:16 ` Christoph Hellwig
2020-09-08 6:16 ` Christoph Hellwig
2020-09-07 15:36 ` [PATCH 4/9] ARM: syscall: always store thread_info->syscall Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-28 9:41 ` Linus Walleij
2020-09-28 9:41 ` Linus Walleij
2020-09-28 12:42 ` Arnd Bergmann
2020-09-28 12:42 ` Arnd Bergmann
2020-09-28 15:08 ` Russell King - ARM Linux admin [this message]
2020-09-28 15:08 ` Russell King - ARM Linux admin
2020-09-07 15:36 ` [PATCH 5/9] ARM: oabi-compat: rework epoll_wait/epoll_pwait emulation Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-08 6:20 ` Christoph Hellwig
2020-09-08 6:20 ` Christoph Hellwig
2020-09-08 20:56 ` Arnd Bergmann
2020-09-08 20:56 ` Arnd Bergmann
2020-09-07 15:36 ` [PATCH 6/9] ARM: oabi-compat: rework sys_semtimedop emulation Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-07 15:36 ` [PATCH 7/9] ARM: oabi-compat: rework fcntl64() emulation Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-07 15:36 ` [PATCH 8/9] ARM: uaccess: add __{get,put}_kernel_nofault Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
2020-09-07 15:36 ` [PATCH 9/9] ARM: uaccess: remove set_fs() implementation Arnd Bergmann
2020-09-07 15:36 ` Arnd Bergmann
-- strict thread matches above, loose matches on Subject: below --
2020-10-30 15:45 [PATCH v4 0/9] ARM: remove set_fs callers and implementation Arnd Bergmann
2020-10-30 15:49 ` [PATCH 1/9] mm/maccess: fix unaligned copy_{from,to}_kernel_nofault Arnd Bergmann
2020-10-30 15:49 ` [PATCH 4/9] ARM: syscall: always store thread_info->syscall Arnd Bergmann
2020-10-30 15:49 ` Arnd Bergmann
2020-10-30 16:53 ` Russell King - ARM Linux admin
2020-10-30 16:53 ` Russell King - ARM Linux admin
2020-10-30 21:28 ` Arnd Bergmann
2020-10-30 21:28 ` Arnd Bergmann
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