From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Andrew Pinski <pinskia@gmail.com>,
Rafael Eduardo Ruviaro Christ
<rafaeleduardoruviaro.christ@asml.com>
Cc: "libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Subject: Re: aarch64 lacks HP_TIMING support in glibc
Date: Tue, 22 Jun 2021 15:57:19 -0300 [thread overview]
Message-ID: <09ae1d8f-7b66-e9fc-5a98-3a002390c298@linaro.org> (raw)
In-Reply-To: <CA+=Sn1nNfa2nrYzS0PdtCTX0K=2d5YD7cyVm7G7GQCZ=ZEbfoQ@mail.gmail.com>
On 22/06/2021 15:38, Andrew Pinski via Libc-alpha wrote:
> On Tue, Jun 22, 2021 at 11:30 AM Rafael Eduardo Ruviaro Christ via
> Libc-alpha <libc-alpha@sourceware.org> wrote:
>>
>> Hello,
>>
>> I noticed that aarch64 lacks HP_TIMING support in glibc. Although this architecture has generic timers, glibc is still using the generic hp-timing.h for aarch64.
>> I see HP_TIMING support for other architectures. I'd like to know why there is no HP_TIMING support for aarch64?
>> Also, if there's planning to support it for aarch64?
>
> See https://sourceware.org/legacy-ml/libc-alpha/2015-06/msg00736.html
> and the previous emails in the thread.
>
Do you have an outcome from kernel regarding it? It seems that the vDSO
seems to use cntvct_el0 regardless, even if it traps for emulation (not
sure if kernel rewrites the vDSO depending of underlying kernel support).
It should be possible support hp-timing.h on aarch64 to use cntvct_el0
if the minimum supported kernel also supports it (3.2). Afaik the
hp-timing will be used only for LD_DEBUG=statistics, so default usage
would not be penalized.
next prev parent reply other threads:[~2021-06-22 18:57 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-22 18:29 Rafael Eduardo Ruviaro Christ
2021-06-22 18:38 ` Andrew Pinski
2021-06-22 18:57 ` Adhemerval Zanella [this message]
2021-06-22 19:27 ` Andreas Schwab
2021-06-22 19:53 ` Adhemerval Zanella
2021-06-22 20:18 ` Andreas Schwab
2021-06-22 20:22 ` Adhemerval Zanella
2021-06-23 11:43 Wilco Dijkstra
2021-06-23 13:26 ` Adhemerval Zanella
2021-06-23 15:19 ` Wilco Dijkstra
2021-06-28 15:49 ` Rafael Eduardo Ruviaro Christ
2021-06-28 19:25 ` Wilco Dijkstra
2021-06-30 13:27 ` Rafael Eduardo Ruviaro Christ
2021-07-02 13:13 ` Wilco Dijkstra
2021-07-02 13:53 ` Adhemerval Zanella
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