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Re: [PATCH 0/1] pc-bios: Support List-Directed IPL from ECKD DASD

From: Jared Rossi
Subject: Re: [PATCH 0/1] pc-bios: Support List-Directed IPL from ECKD DASD
Date: Mon, 20 Feb 2023 10:13:59 -0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0


Pinging this patch since v2.26.0 of s390-tools adds ECKD DASD list-directed IPL.
This patch set allows QEMU to utilize that new boot pointer format.
Any feedback about what needs to be changed for acceptance is much appreciated.

Jared Rossi
On 1/30/23 4:24 PM, Jared Rossi wrote:
Add support for List-Directed IPL (LD-IPL) type pointers.

We check for a boot record indicating LD-IPL and use it if it is valid,
otherwise we use the CCW CDL or LDL format as usual. When a block is accessed
during IPL the block number is first calculated based on the cylinder, head,
and record numbers included in the block pointer; if LD-IPL has been initiated
then each pointer will be interpreted using the new format.

For simplicity, there is no choice presented to forcibly use CCW-IPL if LD-IPL
is available.  Because both sets of pointers ultimately go to the same
kernel/initrd, using CCW- or LD-IPL is transparent to the user.

One aspect of the user experience that does change is the availability of the
interactive boot menu when a loadparm is not specified.  For the existing
CCW-IPL, when the user does not specify a loadparm they are presented with a
list of boot options; however, this list is only written in the old style
pointers.  Therefore, if no loadparm is specified, and LD-IPL is supported, the
default boot option will be used automatically.

Jared Rossi (1):
  pc-bios: Add support for List-Directed IPL from ECKD DASD

 pc-bios/s390-ccw/bootmap.c | 157 ++++++++++++++++++++++++++++---------
 pc-bios/s390-ccw/bootmap.h |  30 ++++++-
 2 files changed, 148 insertions(+), 39 deletions(-)

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