linux-kernel - [PATCH 4.4 19/49] Revert "s390/kdump: Clear subchannel ID to signal non-CCW/SCSI IPL"

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Date:	Sun, 14 Aug 2016 22:23:19 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Steffen Maier <maier@...ux.vnet.ibm.com>,
	Michael Holzheu <holzheu@...ux.vnet.ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	Martin Schwidefsky <schwidefsky@...ibm.com>
Subject: [PATCH 4.4 19/49] Revert "s390/kdump: Clear subchannel ID to signal non-CCW/SCSI IPL"

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Michael Holzheu <holzheu@...ux.vnet.ibm.com>

commit 5419447e2142d6ed68c9f5c1a28630b3a290a845 upstream.

This reverts commit 852ffd0f4e23248b47531058e531066a988434b5.

There are use cases where an intermediate boot kernel (1) uses kexec
to boot the final production kernel (2). For this scenario we should
provide the original boot information to the production kernel (2).
Therefore clearing the boot information during kexec() should not
be done.

Reported-by: Steffen Maier <maier@...ux.vnet.ibm.com>
Signed-off-by: Michael Holzheu <holzheu@...ux.vnet.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@...ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/s390/kernel/ipl.c |    7 -------
 1 file changed, 7 deletions(-)

--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -2070,13 +2070,6 @@ void s390_reset_system(void (*fn_pre)(vo
 	S390_lowcore.program_new_psw.addr =
 		PSW_ADDR_AMODE | (unsigned long) s390_base_pgm_handler;
 
-	/*
-	 * Clear subchannel ID and number to signal new kernel that no CCW or
-	 * SCSI IPL has been done (for kexec and kdump)
-	 */
-	S390_lowcore.subchannel_id = 0;
-	S390_lowcore.subchannel_nr = 0;
-
 	/* Store status at absolute zero */
 	store_status();