bug#49495: 27.2; portable dumper incompatible with 64K pages on aarch64

bug#49495: 27.2; portable dumper incompatible with 64K pages on aarch64

[Dan Čermák]

I am forwarding a bugreport from Fedora, about the portable dumper
causing issues when launching Emacs in a RHEL 8 chroot on aarch64:
(from https://bugzilla.redhat.com/show_bug.cgi?id=1974244)

--8<---------------cut here---------------start------------->8---
The emacs binary from emacs-nox-27.2-2.fc33.aarch64 cannot start in a chroot on Red Hat Enterprise Linux 8 because it assumes 4K pages:

openat(AT_FDCWD, "/usr/bin/emacs-27.2-nox.pdmp", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=10124128, ...}) = 0
read(3, "DUMPEDGNUEMACS\0\0(\304wp;D\330G%\f\265\337\214\264VO"..., 80) = 80
mmap(NULL, 10124128, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff92240000
mmap(0xffff92240000, 6946816, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0xffff92240000
mmap(0xffff928e0000, 90112, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x6a0000) = 0xffff928e0000
mmap(0xffff928f6000, 3087200, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x6b6000) = -1 EINVAL (Invalid argument)

Map offsets and addresses must be a multiple of the page size.
--8<---------------cut here---------------end--------------->8---


Unfortunately, I am not really familiar with Emacs' internals to know
how to handle this bug report.

Cheers,

Dan

bug#49495: 27.2; portable dumper incompatible with 64K pages on aarch64

[Eli Zaretskii]

> From: Dan Čermák <dan.cermak@cgc-instruments.com>
> Date: Fri, 09 Jul 2021 18:38:10 +0200
> 
> I am forwarding a bugreport from Fedora, about the portable dumper
> causing issues when launching Emacs in a RHEL 8 chroot on aarch64:
> (from https://bugzilla.redhat.com/show_bug.cgi?id=1974244)
> 
> --8<---------------cut here---------------start------------->8---
> The emacs binary from emacs-nox-27.2-2.fc33.aarch64 cannot start in a chroot on Red Hat Enterprise Linux 8 because it assumes 4K pages:
> 
> openat(AT_FDCWD, "/usr/bin/emacs-27.2-nox.pdmp", O_RDONLY|O_CLOEXEC) = 3
> fstat(3, {st_mode=S_IFREG|0644, st_size=10124128, ...}) = 0
> read(3, "DUMPEDGNUEMACS\0\0(\304wp;D\330G%\f\265\337\214\264VO"..., 80) = 80
> mmap(NULL, 10124128, PROT_NONE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0xffff92240000
> mmap(0xffff92240000, 6946816, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0) = 0xffff92240000
> mmap(0xffff928e0000, 90112, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x6a0000) = 0xffff928e0000
> mmap(0xffff928f6000, 3087200, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, 3, 0x6b6000) = -1 EINVAL (Invalid argument)
> 
> Map offsets and addresses must be a multiple of the page size.
> --8<---------------cut here---------------end--------------->8---
> 
> 
> Unfortunately, I am not really familiar with Emacs' internals to know
> how to handle this bug report.

Thanks.  Can you try the latest master branch and see if this problem
still happens there?

Daniel, could you please look into this?

bug#49495: 27.2; portable dumper incompatible with 64K pages on aarch64

[Lars Ingebrigtsen]

Eli Zaretskii <eliz@gnu.org> writes:

> Thanks.  Can you try the latest master branch and see if this problem
> still happens there?

This was changed in Emacs 28 a couple months ago:

commit 216c65b135c2b0be7e048cdc6683873b03b99b9a
Author:     Lars Ingebrigtsen <larsi@gnus.org>
AuthorDate: Sun Mar 28 19:13:00 2021 +0200

    Use a 64KB page size for pdump
    
    * src/pdumper.c (dump_get_page_size): Use a 64KB page size on all
    architectures, as this many vary between systems (bug#47125).

So I think the problem should be fixed now, but it'd be good to get it
confirmed. 

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#49495: 27.2; portable dumper incompatible with 64K pages on aarch64

[Dan Čermák]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> Eli Zaretskii <eliz@gnu.org> writes:
>
>> Thanks.  Can you try the latest master branch and see if this problem
>> still happens there?
>
> This was changed in Emacs 28 a couple months ago:
>
> commit 216c65b135c2b0be7e048cdc6683873b03b99b9a
> Author:     Lars Ingebrigtsen <larsi@gnus.org>
> AuthorDate: Sun Mar 28 19:13:00 2021 +0200
>
>     Use a 64KB page size for pdump
>     
>     * src/pdumper.c (dump_get_page_size): Use a 64KB page size on all
>     architectures, as this many vary between systems (bug#47125).
>
> So I think the problem should be fixed now, but it'd be good to get it
> confirmed.

This appears to fix this issue. Thanks!

bug#49495: 27.2; portable dumper incompatible with 64K pages on aarch64

[Eli Zaretskii]

> From: Dan Čermák <dan.cermak@cgc-instruments.com>
> Cc: Daniel Colascione <dancol@dancol.org>, 49495@debbugs.gnu.org
> Date: Sat, 17 Jul 2021 11:45:46 +0200
> 
> > commit 216c65b135c2b0be7e048cdc6683873b03b99b9a
> > Author:     Lars Ingebrigtsen <larsi@gnus.org>
> > AuthorDate: Sun Mar 28 19:13:00 2021 +0200
> >
> >     Use a 64KB page size for pdump
> >     
> >     * src/pdumper.c (dump_get_page_size): Use a 64KB page size on all
> >     architectures, as this many vary between systems (bug#47125).
> >
> > So I think the problem should be fixed now, but it'd be good to get it
> > confirmed.
> 
> This appears to fix this issue. Thanks!

Thanks, so I'm closing this bug report.