linux-kernel - Re: [PATCH v9 1/1] efi: a misc char interface for user to update efi firmware

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Date:	Tue, 3 Nov 2015 20:59:34 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"Kweh, Hock Leong" <hock.leong.kweh@...el.com>
Cc:	Matt Fleming <matt@...sole-pimps.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	"Ong, Boon Leong" <boon.leong.ong@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	Sam Protsenko <semen.protsenko@...aro.org>,
	Peter Jones <pjones@...hat.com>,
	Andy Lutomirski <luto@...capital.net>,
	Roy Franz <roy.franz@...aro.org>,
	James Bottomley <James.Bottomley@...senpartnership.com>,
	Linux FS Devel <linux-fsdevel@...r.kernel.org>,
	"Fleming, Matt" <matt.fleming@...el.com>,
	"Anvin, H Peter" <h.peter.anvin@...el.com>
Subject: Re: [PATCH v9 1/1] efi: a misc char interface for user to update efi
 firmware

On Mon, Nov 02, 2015 at 06:47:29AM +0000, Kweh, Hock Leong wrote:
> By looking at your dmesg log, the above print out message seem that
> someone has called the flush() after the write(2). In my environment, flush()
> only being called in 2 places which are before write(2) and during close(2).
> The dmesg log seems that your environment is running write(2) and flush() in
> different threads and are parallel. Could you help me to double confirm this and it 
> would be good if you could told me when the flush() is exactly being called in
> your environment. The info really help me on debugging.

I don't know what you mean: I simply do

cat /bin/ls > /dev/efi_capsule_loader

as root in an SMP kvm guest. And it explodes. Nothing special, just this
one command.

I guess you could try to reproduce it, here's how I start it:

qemu-system-x86_64
-enable-kvm
-gdb tcp::1234
-cpu Opteron_G5
-m 2048
-hda /home/boris/kvm/debian/sid-x86_64.img
-hdb /home/boris/kvm/swap.img
-boot menu=off,order=c
-localtime
-net nic,model=rtl8139
-net user,hostfwd=tcp::1235-:22
-usbdevice tablet
-kernel /home/boris/kernel/linux-2.6/arch/x86/boot/bzImage
-append "root=/dev/sda1 resume=/dev/sdb1 debug ignore_loglevel log_buf_len=16M earlyprintk=ttyS0,115200 console=ttyS0,115200 console=tty0"
-monitor pty
-virtfs local,path=/tmp,mount_tag=tmp,security_model=none
-serial file:/home/boris/kvm/test-x86_64-1235.log
-snapshot
-smp 8

HTH.

-- 
Regards/Gruss,
    Boris.

ECO tip #101: Trim your mails when you reply.
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