Linux SNPS ARC Archive on lore.kernel.org
 help / color / Atom feed
From: Vineet Gupta <Vineet.Gupta1@synopsys.com>
To: Joseph Myers <joseph@codesourcery.com>,
	Vineet Gupta <Vineet.Gupta1@synopsys.com>
Cc: arcml <linux-snps-arc@lists.infradead.org>,
	"libc-alpha@sourceware.org" <libc-alpha@sourceware.org>
Subject: Re: [PATCH v7.1 07/13] ARC: Linux Syscall Interface
Date: Tue, 7 Jul 2020 23:16:29 +0000
Message-ID: <914e73fd-27dd-14b7-841c-66f9501adde3@synopsys.com> (raw)
In-Reply-To: <alpine.DEB.2.21.2007072128060.16069@digraph.polyomino.org.uk>

On 7/7/20 2:32 PM, Joseph Myers wrote:
> On Tue, 7 Jul 2020, Vineet Gupta via Libc-alpha wrote:
> 
>>> Each implementation has it ows requirements so I can't really say if
>>> a helper function does make sense for all of them.  For pause
>>> specifically we can even simplify to since all architectures have
>>> either ppoll or ppoll_time64:
>>>
>>>   int
>>>   __libc_pause (void)
>>>   {
>>>   #ifdef __NR_ppoll_time64
>>>     return SYSCALL_CANCEL (ppoll_time64, NULL, 0, NULL, NULL);
>>>   #else
>>>     return SYSCALL_CANCEL (ppoll, NULL, 0, NULL, NULL);
>>>   #endif
>>>   }
>>
>> But how is this compatible with older kernels (and perhaps this is a general
>> question). I mean one/more ABIs minimum kernel would not have the ppoll or ppoll64
>> so how will new glibc work with such a kernel ? Is it not required to ?
> 
> See commit 089b772f98afd9eb6264c6489bc96a30bf6af4ac, where I removed 
> __ASSUME_PPOLL because all supported kernel versions now had that syscall 
> for all glibc architectures.

But that still doesn't explain how new glibc works with old kernels (for say when
a port support was first merged, with say asm-generic ABI).

Ah it seems any glibc is only required to work with "arch_minimum_kernel" (generic
or architecture override) which over time itself keeps moving forward due to
various reasons (e.g. 64-bit time support etc). So indeed a bleeding edge glibc of
today won't necessarily work with an arch kernel for say when its glibc port was
first merged, but will for the corresponding arch_minimum_kernel.

> In general this sort of thing needs a review of whether a given syscall is 
> available for all glibc architectures in their minimum kernel versions.  
> For the old kernels in question, that means checking the 
> architecture-specific syscall table as used to dispatch syscalls at 
> runtime, which used to have an architecture-specific format before 
> unification work was done; it used to mean checking asm/unistd.h as well, 
> but now we have syscall tables in glibc that's probably no longer 
> required.  It also involves checking compat syscall tables for 32-bit 
> binaries on 64-bit kernels, as sometimes a syscall didn't get added to the 
> native and compat syscall tables at the same time (see the comments in 
> sparc/kernel-features.h about various socket-related syscalls, for 
> example).
> 

_______________________________________________
linux-snps-arc mailing list
linux-snps-arc@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-snps-arc

  reply index

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-15 20:14 [PATCH v7 00/13] glibc port to ARC processors Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 01/13] ARC: ABI Implementation Vineet Gupta
2020-07-01  0:06   ` [PATCH v7.1 " Vineet Gupta
     [not found]     ` <b6322150-240a-5f06-b700-83e3eb79deec@linaro.org>
2020-07-01 19:36       ` Vineet Gupta
2020-07-01 19:45         ` Adhemerval Zanella
2020-06-15 20:14 ` [PATCH v7 02/13] ARC: startup and dynamic linking code Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 03/13] ARC: Thread Local Storage support Vineet Gupta
2020-07-01  0:07   ` [PATCH v7.1 " Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 04/13] ARC: Atomics and Locking primitives Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 05/13] ARC: math soft float support Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 06/13] ARC: hardware floating point support Vineet Gupta
2020-07-01  0:08   ` [PATCH v7.1 " Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 07/13] ARC: Linux Syscall Interface Vineet Gupta
2020-07-01  0:08   ` [PATCH v7.1 " Vineet Gupta
     [not found]     ` <e9e2ae28-cd78-5924-c1fa-52b1499c245a@linaro.org>
2020-07-04  3:54       ` Vineet Gupta
2020-07-06 13:20         ` Adhemerval Zanella
2020-07-07  1:25           ` Vineet Gupta
2020-07-07 19:24             ` Adhemerval Zanella
2020-07-07 20:55               ` [PATCH v7.2 " Vineet Gupta
     [not found]                 ` <b64d0df1-4229-d619-0ab1-ded287323775@linaro.org>
2020-07-08 19:32                   ` Vineet Gupta
2020-07-09 16:03                     ` Adhemerval Zanella
2020-07-09 16:24                       ` Vineet Gupta
2020-07-09 16:25                         ` Adhemerval Zanella
2020-07-09 21:13                         ` Vineet Gupta
2020-07-09 21:36                           ` ARC testsuite regressions (was Re: [PATCH v7.2 07/13] ARC: Linux Syscall Interface) Vineet Gupta
2020-07-09 22:01                             ` Alistair Francis
2020-07-09 22:16                               ` Vineet Gupta
2020-07-10  9:28                               ` Florian Weimer
2020-07-10 15:53                                 ` Vineet Gupta
2020-07-10 17:02                                   ` Florian Weimer
2020-07-10 20:07                                     ` Vineet Gupta
2020-07-10 20:32                                       ` Florian Weimer
2020-07-10 19:12                                   ` Alistair Francis
2020-07-10 20:33                                     ` Florian Weimer
2020-07-10 20:56                                       ` Alistair Francis
2020-07-10 19:10                                 ` Alistair Francis
2020-07-07 21:07               ` [PATCH v7.1 07/13] ARC: Linux Syscall Interface Vineet Gupta
2020-07-07 21:32                 ` Joseph Myers
2020-07-07 23:16                   ` Vineet Gupta [this message]
2020-06-15 20:14 ` [PATCH v7 08/13] ARC: Linux ABI Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 09/13] ARC: Linux Startup and Dynamic Loading Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 10/13] ARC: ABI lists Vineet Gupta
2020-07-01  0:09   ` [PATCH v7.1 " Vineet Gupta
2020-06-15 20:14 ` [PATCH v7 11/13] ARC: Build Infrastructure Vineet Gupta
2020-07-03 17:09   ` Adhemerval Zanella
2020-06-15 20:14 ` [PATCH v7 12/13] build-many-glibcs.py: Enable ARC builds Vineet Gupta
2020-07-03 17:37   ` Adhemerval Zanella
2020-06-15 20:14 ` [PATCH v7 13/13] Documentation for ARC port Vineet Gupta
2020-07-03 17:38   ` Adhemerval Zanella
2020-06-23 16:56 ` [PATCH v7 00/13] glibc port to ARC processors Vineet Gupta
2020-07-01  0:11   ` Vineet Gupta
2020-07-01  1:44     ` Adhemerval Zanella
2020-07-01 19:13       ` Vineet Gupta
2020-07-02  1:00         ` ARC math test regressions (was Re: [PATCH v7 00/13] glibc port to ARC processors) Vineet Gupta
2020-07-02  7:17           ` Andreas Schwab
2020-07-02 16:27           ` Joseph Myers
2020-07-02 17:45             ` Vineet Gupta
2020-07-02 21:27       ` [PATCH v7 00/13] glibc port to ARC processors Joseph Myers

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=914e73fd-27dd-14b7-841c-66f9501adde3@synopsys.com \
    --to=vineet.gupta1@synopsys.com \
    --cc=joseph@codesourcery.com \
    --cc=libc-alpha@sourceware.org \
    --cc=linux-snps-arc@lists.infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

Linux SNPS ARC Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/linux-snps-arc/0 linux-snps-arc/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 linux-snps-arc linux-snps-arc/ https://lore.kernel.org/linux-snps-arc \
		linux-snps-arc@lists.infradead.org
	public-inbox-index linux-snps-arc

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.infradead.lists.linux-snps-arc


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git