From: Jan Beulich <jbeulich@suse.com>
To: Bertrand Marquis <Bertrand.Marquis@arm.com>
Cc: "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
Andrew Cooper <andrew.cooper3@citrix.com>,
George Dunlap <george.dunlap@citrix.com>,
Julien Grall <julien@xen.org>,
Stefano Stabellini <sstabellini@kernel.org>, Wei Liu <wl@xen.org>
Subject: Re: [PATCH RFC] EFI: strip xen.efi when putting it on the EFI partition
Date: Tue, 26 Apr 2022 16:09:31 +0200 [thread overview]
Message-ID: <07281533-7967-bf67-d68c-3ce1bd5de157@suse.com> (raw)
In-Reply-To: <DFF300CA-944E-47D9-9674-6858790D45C2@arm.com>
On 26.04.2022 14:26, Bertrand Marquis wrote:
> Hi Jan,
>
>> On 25 Apr 2022, at 11:46, Jan Beulich <jbeulich@suse.com> wrote:
>>
>> With debug info retained, xen.efi can be quite large. Unlike for xen.gz
>> there's no intermediate step (mkelf32 there) involved which would strip
>> debug info kind of as a side effect. While the installing of xen.efi on
>> the EFI partition is an optional step (intended to be a courtesy to the
>> developer), adjust it also for the purpose of documenting what distros
>> would be expected to do during boot loader configuration (which is what
>> would normally put xen.efi into the EFI partition).
>>
>> Model the control over stripping after Linux'es module installation,
>> except that the stripped executable is constructed in the build area
>> instead of in the destination location. This is to conserve on space
>> used there - EFI partitions tend to be only a few hundred Mb in size.
>>
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>> ---
>> RFC: GNU strip 2.38 appears to have issues when acting on a PE binary:
>> - the new file positions of the sections do not respect the file
>> alignment specified by the header (a resulting looks to work on
>> one EFI implementation where I did actually try it, but I don't
>> think we can rely on that),
>> - file name symbols are also stripped; while there is a separate
>> --keep-file-symbols option (which I would have thought to be on
>> by default anyway), its use makes no difference.
>> Older GNU strip (observed with 2.35.1) doesn't work at all ("Data
>> Directory size (1c) exceeds space left in section (8)").
>>
>> --- a/xen/Makefile
>> +++ b/xen/Makefile
>> @@ -461,6 +461,22 @@ endif
>> .PHONY: _build
>> _build: $(TARGET)$(CONFIG_XEN_INSTALL_SUFFIX)
>>
>> +# Strip
>> +#
>> +# INSTALL_EFI_STRIP, if defined, will cause xen.efi to be stripped before it
>> +# is installed. If INSTALL_EFI_STRIP is '1', then the default option
>> +# --strip-debug will be used. Otherwise, INSTALL_EFI_STRIP value will be used
>> +# as the option(s) to the strip command.
>> +ifdef INSTALL_EFI_STRIP
>> +
>> +ifeq ($(INSTALL_EFI_STRIP),1)
>> +efi-strip-opt := --strip-debug
>> +else
>> +efi-strip-opt := $(INSTALL_EFI_STRIP)
>> +endif
>> +
>> +endif
>
> This does sound very complex and using combination of ifdef and ifeq on an external variable is not done anywhere else.
>
> How about splitting into a variable to turn strip on or off and let the user override a local variable setting up the strip options if he wants to ?
>
> Something like:
>
> EFI_STRIP_OPTION ?= "—strip-debug"
>
> And then just using INSTALL_EFI_STRIP to strip or not during the _install phase
This "just using INSTALL_EFI_STRIP" is what we have with the present
version as well, and I'm not really looking forward to have two
separate variable to act upon. It was for this particular reason that
I took Linux'es module installation process as a "template".
> One wanting to use no specific option would have to pass INSTALL_EFI_STRIP=1 EFI_STRIP_OPTION=“” for example.
This particular example wouldn't strip anything aiui, and hence would
needlessly touch the binary (and perhaps make changes to it just as a
side effect: For example I'm observing the string table growing, which
I have yet to investigate in binutils).
Jan
next prev parent reply other threads:[~2022-04-26 14:09 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-25 10:46 [PATCH RFC] EFI: strip xen.efi when putting it on the EFI partition Jan Beulich
2022-04-26 12:26 ` Bertrand Marquis
2022-04-26 14:09 ` Jan Beulich [this message]
2022-04-26 14:52 ` Bertrand Marquis
2022-05-02 14:47 ` Jan Beulich
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