Hi Nicolas, hi John,
during tests of hardware watchpoint support for GDB I run into a couple of Linux kernel issues:
- On (some versions of?) Versatile Express SMP Cortex-A9 SMP boards, a CPU errata (#720789) causes TLB flushes to sometime fail, which can lead to random problems when running GDB in SMP mode (and probably elsewhere). There is a kernel work-around for this problem activated by CONFIG_ARM_ERRATA_720789, but this is unfortuantely not active on the Linaro kernels. (On OMAP4, this happens automatically due to an entry in mach-omap2/Kconfig. There is no such entry in mach-vexpress/Kconfig currently.)
- On machines that do not support watchpoints (e.g. IGEP with current kernels), this fact is not reported properly to user space. Will Deacon posted a patch to fix this: http://lists.infradead.org/pipermail/linux-arm-kernel/2011-February/041492.h...
Can we get fixes for these issues included in the Linaro kernel (git tree and/or packages ... not sure where the best place would be)?
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
-- Dr. Ulrich Weigand | Phone: +49-7031/16-3727 STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E. IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martin Jetter | Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen | Registergericht: Amtsgericht Stuttgart, HRB 243294
On Mon, 21 Feb 2011, Ulrich Weigand wrote:
Hi Nicolas, hi John,
during tests of hardware watchpoint support for GDB I run into a couple of Linux kernel issues:
- On (some versions of?) Versatile Express SMP Cortex-A9 SMP boards, a CPU
errata (#720789) causes TLB flushes to sometime fail, which can lead to random problems when running GDB in SMP mode (and probably elsewhere). There is a kernel work-around for this problem activated by CONFIG_ARM_ERRATA_720789, but this is unfortuantely not active on the Linaro kernels. (On OMAP4, this happens automatically due to an entry in mach-omap2/Kconfig. There is no such entry in mach-vexpress/Kconfig currently.)
Could you send a patch to Russell for that?
- On machines that do not support watchpoints (e.g. IGEP with current
kernels), this fact is not reported properly to user space. Will Deacon posted a patch to fix this: http://lists.infradead.org/pipermail/linux-arm-kernel/2011-February/041492.h...
Can we get fixes for these issues included in the Linaro kernel (git tree and/or packages ... not sure where the best place would be)?
This is included in the Linaro kernel repository already:
http://git.linaro.org/gitweb?p=kernel/linux-linaro-2.6.37.git%3Ba=commit%3Bh...
Next packaging of the kernel will pick it up.
Nicolas
- On (some versions of?) Versatile Express SMP Cortex-A9 SMP boards, a CPU
errata (#720789) causes TLB flushes to sometime fail, which can lead to random problems when running GDB in SMP mode (and probably elsewhere). There is a kernel work-around for this problem activated by CONFIG_ARM_ERRATA_720789, but this is unfortuantely not active on the Linaro kernels. (On OMAP4, this happens automatically due to an entry in mach-omap2/Kconfig. There is no such entry in mach-vexpress/Kconfig currently.)
Could you send a patch to Russell for that?
I have a patch that enables some other workarounds that we probably want enabled for the VE as well. I can CC you (Ulrich) on that if you'd prefer?
Will
Nicolas Pitre nicolas.pitre@linaro.org wrote on 02/21/2011 06:48:10 PM:
This is included in the Linaro kernel repository already:
http://git.linaro.org/gitweb?p=kernel/linux-linaro-2.6. 37.git;a=commit;h=40ef21c84e
Next packaging of the kernel will pick it up.
Ah, I missed that, sorry. Thanks!
Mit freundlichen Gruessen / Best Regards
Ulrich Weigand
-- Dr. Ulrich Weigand | Phone: +49-7031/16-3727 STSM, GNU compiler and toolchain for Linux on System z and Cell/B.E. IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martin Jetter | Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen | Registergericht: Amtsgericht Stuttgart, HRB 243294
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Nicolas Pitre -
Ulrich Weigand -
Will Deacon