From: Chad Reese <kreese@caviumnetworks.com>
To: Ralf Baechle <ralf@linux-mips.org>
Cc: David Daney <ddaney@caviumnetworks.com>,
Christoph Hellwig <hch@lst.de>,
linux-mips@linux-mips.org,
Tomaso Paoletti <tpaoletti@caviumnetworks.com>
Subject: Re: [PATCH 06/36] Add Cavium OCTEON processor CSR definitions
Date: Thu, 30 Oct 2008 11:45:39 -0700 [thread overview]
Message-ID: <490A00D3.50003@caviumnetworks.com> (raw)
In-Reply-To: <20081030111354.GF26256@linux-mips.org>
Ralf Baechle wrote:
> You see, everything was defined twice. And gcc even recent gccs tend to
> do silly stuff with bitfields when combined with volatile:
Nobody should be using volatile anyway. It doesn't supply anywhere close
to the needed control for a register access. C would be a better
language if the volatile keyword was removed.
> The Linux programming programming model relies on accessor functions like
> readl, ioread32 etc. Those take addresses as arguments - but bitfields
> don't have addresses in C ...
It is not valid on Octeon to access parts of CSR registers. You must do
a 64bit access, change whatever fields you want, and store the new
value. For this model bitfields work very well. GCC converts the
bitfield operations into bit insert and extract for mips64r2. It also
automatically combines multiple field sets into a single immediate load.
> So exec summary: bitfields bad for such low-level stuff.
Having spent a few years programming Octeon in various ways, bitfields
work really well for it.
Chad
next prev parent reply other threads:[~2008-10-30 18:46 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-27 23:58 [PATCH 00/36] Add Cavium OCTEON processor support (v2) David Daney
2008-10-28 0:02 ` [PATCH 01/36] Add Cavium OCTEON processor support files to arch/mips/cavium-octeon David Daney
2008-10-28 0:02 ` [PATCH 02/36] Add Cavium OCTEON files to arch/mips/include/asm/mach-cavium-octeon David Daney
2008-10-28 0:02 ` [PATCH 03/36] Add Cavium OCTEON processor support files to arch/mips/kernel David Daney
2008-10-28 0:02 ` [PATCH 04/36] Add Cavium OCTEON processor support files to arch/mips/mm David Daney
2008-10-28 0:02 ` [PATCH 05/36] Add Cavium OCTEON processor support files to and arch/mips/cavium-octeon/executive David Daney
2008-10-28 0:02 ` [PATCH 06/36] Add Cavium OCTEON processor CSR definitions David Daney
2008-10-28 0:02 ` [PATCH 07/36] Don't assume boot CPU is CPU0 if MIPS_DISABLE_BOOT_CPU_ZERO set David Daney
2008-10-28 0:02 ` [PATCH 08/36] For Cavium OCTEON handle hazards as per the R10000 handling David Daney
2008-10-28 0:02 ` [PATCH 09/36] Enable mips32 style bitops for Cavium OCTEON David Daney
2008-10-28 0:02 ` [PATCH 10/36] Cavium OCTEON: Set hwrena and lazily restore CP2 state David Daney
2008-10-28 0:02 ` [PATCH 11/36] MIPSR2 ebase isn't just CAC_BASE David Daney
2008-10-28 0:02 ` [PATCH 12/36] Add Cavium OCTEON to arch/mips/Kconfig David Daney
2008-10-28 0:02 ` [PATCH 13/36] Add Cavium OCTEON processor constants David Daney
2008-10-28 0:02 ` [PATCH 14/36] Rewrite cpu_to_name so it has one statement per line David Daney
2008-10-28 0:02 ` [PATCH 15/36] Probe for Cavium OCTEON CPUs David Daney
2008-10-28 0:02 ` [PATCH 16/36] MIPS: Hook Cavium OCTEON cache init into cache.c David Daney
2008-10-28 0:02 ` [PATCH 17/36] cavium: Hook Cavium specifics into main arch/mips dir David Daney
2008-10-28 0:02 ` [PATCH 18/36] Cavium OCTEON modify core io.h macros to account for the Octeon Errata Core-301 David Daney
2008-10-28 0:02 ` [PATCH 19/36] Cavium OCTEON: increase MAX_DMA address David Daney
2008-10-28 0:02 ` [PATCH 20/36] Cavium OCTEON: add in icache and dcache error functions David Daney
2008-10-28 0:02 ` [PATCH 21/36] Cavium OCTEON: Add cop2/cvmseg state entries to processor.h David Daney
2008-10-28 0:02 ` [PATCH 22/36] Add Cavium OCTEON specific registers to ptrace.h and asm-offsets.c David Daney
2008-10-28 0:02 ` [PATCH 23/36] Add SMP_ICACHE_FLUSH for the Cavium CPU family David Daney
2008-10-28 0:02 ` [PATCH 24/36] Cavium OCTEON: PT vs MFC0 reorder, multiplier state preservation David Daney
2008-10-28 0:02 ` [PATCH 25/36] Add Cavium OCTEON irq hazard in asmmacro.h David Daney
2008-10-28 0:02 ` [PATCH 26/36] Compute branch returns for Cavium OCTEON specific branch instructions David Daney
2008-10-28 0:02 ` [PATCH 27/36] Add Cavium OCTEON slot into proper tlb category David Daney
2008-10-28 0:03 ` [PATCH 28/36] MIPS: move FPU emulator externs to fpu_emulator.h David Daney
2008-10-28 0:03 ` [PATCH 29/36] Cavium OCTEON FPU EMU exception as TLB exception David Daney
2008-10-28 16:06 ` Ralf Baechle
2008-10-30 11:44 ` [PATCH 17/36] cavium: Hook Cavium specifics into main arch/mips dir Ralf Baechle
2008-10-29 12:17 ` [PATCH 15/36] Probe for Cavium OCTEON CPUs Ralf Baechle
2008-10-29 16:18 ` David Daney
2008-10-29 16:26 ` Ralf Baechle
2008-10-29 16:31 ` David Daney
2008-10-29 17:10 ` Ralf Baechle
2008-10-29 19:24 ` Maciej W. Rozycki
2008-10-29 17:38 ` Sergei Shtylyov
2008-10-28 9:56 ` [PATCH 11/36] MIPSR2 ebase isn't just CAC_BASE Ralf Baechle
2008-10-28 16:05 ` Maciej W. Rozycki
2008-10-28 16:13 ` Chad Reese
2008-10-28 16:13 ` Chad Reese
2008-10-28 16:27 ` Ralf Baechle
2008-10-28 17:29 ` Maciej W. Rozycki
2008-10-29 7:38 ` Brian Foster
2008-10-28 16:21 ` Ralf Baechle
2008-10-28 17:30 ` Maciej W. Rozycki
2008-10-28 7:30 ` [PATCH 09/36] Enable mips32 style bitops for Cavium OCTEON Ralf Baechle
2008-10-28 6:47 ` [PATCH 07/36] Don't assume boot CPU is CPU0 if MIPS_DISABLE_BOOT_CPU_ZERO set Ralf Baechle
2008-10-28 16:43 ` David Daney
2008-10-28 17:28 ` Ralf Baechle
2008-10-29 18:45 ` [PATCH 06/36] Add Cavium OCTEON processor CSR definitions Christoph Hellwig
2008-10-29 19:18 ` David Daney
2008-10-29 19:27 ` Christoph Hellwig
2008-10-29 20:53 ` Chad Reese
2008-10-30 11:13 ` Ralf Baechle
2008-10-30 18:21 ` David Daney
2008-10-30 18:45 ` Chad Reese [this message]
2008-10-29 18:45 ` [PATCH 05/36] Add Cavium OCTEON processor support files to and arch/mips/cavium-octeon/executive Christoph Hellwig
2008-10-29 23:03 ` Sergei Shtylyov
2008-10-30 17:19 ` Christoph Hellwig
2008-10-30 18:23 ` Sergei Shtylyov
2008-10-30 22:16 ` Christoph Hellwig
2008-10-29 16:07 ` [PATCH 04/36] Add Cavium OCTEON processor support files to arch/mips/mm Ralf Baechle
2008-10-29 16:25 ` David Daney
2008-10-29 18:09 ` Ralf Baechle
2008-10-30 21:17 ` David Daney
2008-10-28 7:57 ` [PATCH 02/36] Add Cavium OCTEON files to arch/mips/include/asm/mach-cavium-octeon Ralf Baechle
2008-10-28 10:36 ` Sergei Shtylyov
2008-10-28 16:02 ` Maciej W. Rozycki
2008-10-28 16:17 ` Ralf Baechle
2008-10-28 17:24 ` Maciej W. Rozycki
2008-10-28 23:51 ` David Daney
2008-10-29 1:29 ` Ralf Baechle
2008-10-28 0:04 ` [PATCH 30/36] Don't clobber spinlocks in 8250 David Daney
2008-10-28 0:04 ` [PATCH 31/36] Generic 8250 serial driver changes to support future OCTEON serial patches David Daney
2008-10-28 0:04 ` [PATCH 32/36] Allow port type to be specified when calling serial8250_register_port David Daney
2008-10-28 0:04 ` [PATCH 33/36] Allow port type to specify bugs that are not probed for David Daney
2008-10-28 0:04 ` [PATCH 34/36] 8250 serial driver changes for Cavium OCTEON David Daney
2008-10-28 0:04 ` [PATCH 35/36] Adjust the dma-common.c platform hooks David Daney
2008-10-28 0:04 ` [PATCH 36/36] Add defconfig for Cavium OCTEON David Daney
2008-10-29 19:15 ` [PATCH 00/36] Add Cavium OCTEON processor support (v2) Maciej W. Rozycki
2008-10-30 15:01 ` Chris Friesen
2008-11-04 14:48 ` Maciej W. Rozycki
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