[v4,03/10] s390-ccw: refactor IPL structs

Commit Message

Collin L. Walling Jan. 23, 2018, 6:26 p.m. UTC

ECKD DASDs have different IPL structures for CDL and LDL
formats. The current Ipl1 and Ipl2 structs follow the CDL
format, so we prepend "EckdCdl" to them. Boot info for LDL
has been moved to a new struct: EckdLdlIpl1.

Also introduce structs for IPL stages 1 and 1b.

Signed-off-by: Collin L. Walling <[e-mail]>
Acked-by: Janosch Frank <[e-mail]>
---
 pc-bios/s390-ccw/bootmap.c | 12 +++++-----
 pc-bios/s390-ccw/bootmap.h | 55 ++++++++++++++++++++++++++++++++--------------
 2 files changed, 45 insertions(+), 22 deletions(-)

Comments

Thomas Huth Jan. 25, 2018, 11:39 a.m. UTC | #1

On 23.01.2018 19:26, Collin L. Walling wrote:
> ECKD DASDs have different IPL structures for CDL and LDL
> formats. The current Ipl1 and Ipl2 structs follow the CDL
> format, so we prepend "EckdCdl" to them. Boot info for LDL
> has been moved to a new struct: EckdLdlIpl1.
> 
> Also introduce structs for IPL stages 1 and 1b.

I'd maybe move the 1b stuff into a later patch, when you really need it.

By the way, is there a public spec available somewhere for these ECKD
boot structures?

Anyway, patch looks fine to me, so:

Reviewed-by: Thomas Huth <[e-mail]>

Collin L. Walling Jan. 25, 2018, 3:13 p.m. UTC | #2

On 01/25/2018 06:39 AM, Thomas Huth wrote:
> On 23.01.2018 19:26, Collin L. Walling wrote:
>> ECKD DASDs have different IPL structures for CDL and LDL
>> formats. The current Ipl1 and Ipl2 structs follow the CDL
>> format, so we prepend "EckdCdl" to them. Boot info for LDL
>> has been moved to a new struct: EckdLdlIpl1.
>>
>> Also introduce structs for IPL stages 1 and 1b.
> I'd maybe move the 1b stuff into a later patch, when you really need it.

Makes sense to me.

>
> By the way, is there a public spec available somewhere for these ECKD
> boot structures?

The zipl source code should be available if you have the time and
want to understand the nitty-gritty of how all the data gets written.

https://github.com/ibm-s390-tools/s390-tools/tree/master/zipl

I'm also fairly confident we have a document available /somewhere/...
I'll ask around and provide something for you ASAP.

>
> Anyway, patch looks fine to me, so:
>
> Reviewed-by: Thomas Huth <[e-mail]>
>

Thanks for the review!

Patch

diff --git a/pc-bios/s390-ccw/bootmap.c b/pc-bios/s390-ccw/bootmap.c
index 621adbe..b01e0f6 100644
--- a/pc-bios/s390-ccw/bootmap.c
+++ b/pc-bios/s390-ccw/bootmap.c
@@ -221,7 +221,7 @@  static void run_eckd_boot_script(block_number_t bmt_block_nr)
 static void ipl_eckd_cdl(void)
 {
     XEckdMbr *mbr;
-    Ipl2 *ipl2 = (void *)sec;
+    EckdCdlIpl2 *ipl2 = (void *)sec;
     IplVolumeLabel *vlbl = (void *)sec;
     block_number_t bmt_block_nr;
 
@@ -231,7 +231,7 @@  static void ipl_eckd_cdl(void)
     memset(sec, FREE_SPACE_FILLER, sizeof(sec));
     read_block(1, ipl2, "Cannot read IPL2 record at block 1");
 
-    mbr = &ipl2->u.x.mbr;
+    mbr = &ipl2->mbr;
     IPL_assert(magic_match(mbr, ZIPL_MAGIC), "No zIPL section in IPL2 record.");
     IPL_assert(block_size_ok(mbr->blockptr.xeckd.bptr.size),
                "Bad block size in zIPL section of IPL2 record.");
@@ -281,7 +281,7 @@  static void print_eckd_ldl_msg(ECKD_IPL_mode_t mode)
 static void ipl_eckd_ldl(ECKD_IPL_mode_t mode)
 {
     block_number_t bmt_block_nr;
-    BootInfo *bip = (void *)(sec + 0x70); /* BootInfo is MBR for LDL */
+    EckdLdlIpl1 *ipl1 = (void *)sec;
 
     if (mode != ECKD_LDL_UNLABELED) {
         print_eckd_ldl_msg(mode);
@@ -292,15 +292,15 @@  static void ipl_eckd_ldl(ECKD_IPL_mode_t mode)
     memset(sec, FREE_SPACE_FILLER, sizeof(sec));
     read_block(0, sec, "Cannot read block 0 to grab boot info.");
     if (mode == ECKD_LDL_UNLABELED) {
-        if (!magic_match(bip->magic, ZIPL_MAGIC)) {
+        if (!magic_match(ipl1->bip.magic, ZIPL_MAGIC)) {
             return; /* not applicable layout */
         }
         sclp_print("unlabeled LDL.\n");
     }
-    verify_boot_info(bip);
+    verify_boot_info(&ipl1->bip);
 
     /* save pointer to Boot Map Table */
-    bmt_block_nr = eckd_block_num(bip->bp.ipl.bm_ptr.eckd.bptr.chs);
+    bmt_block_nr = eckd_block_num(ipl1->bip.bp.ipl.bm_ptr.eckd.bptr.chs);
 
     run_eckd_boot_script(bmt_block_nr);
     /* no return */
diff --git a/pc-bios/s390-ccw/bootmap.h b/pc-bios/s390-ccw/bootmap.h
index 260ac2a..460ec1a 100644
--- a/pc-bios/s390-ccw/bootmap.h
+++ b/pc-bios/s390-ccw/bootmap.h
@@ -237,22 +237,45 @@  typedef struct BootInfo {          /* @ 0x70, record #0    */
     } bp;
 } __attribute__ ((packed)) BootInfo; /* see also XEckdMbr   */
 
-typedef struct Ipl1 {
-    unsigned char key[4]; /* == "IPL1" */
-    unsigned char data[24];
-} __attribute__((packed)) Ipl1;
-
-typedef struct Ipl2 {
-    unsigned char key[4]; /* == "IPL2" */
-    union {
-        unsigned char data[144];
-        struct {
-            unsigned char reserved1[92-4];
-            XEckdMbr mbr;
-            unsigned char reserved2[144-(92-4)-sizeof(XEckdMbr)];
-        } x;
-    } u;
-} __attribute__((packed)) Ipl2;
+/*
+ * Structs for IPL
+ */
+#define STAGE2_BLK_CNT_MAX  24 /* Stage 1b can load up to 24 blocks */
+
+typedef struct EckdCdlIpl1 {
+    uint8_t key[4]; /* == "IPL1" */
+    uint8_t data[24];
+} __attribute__((packed)) EckdCdlIpl1;
+
+typedef struct EckdSeekArg {
+    uint16_t pad;
+    EckdCHS chs;
+    uint8_t pad2;
+} __attribute__ ((packed)) EckdSeekArg;
+
+typedef struct EckdStage1b {
+    uint8_t reserved[32 * STAGE2_BLK_CNT_MAX];
+    struct EckdSeekArg seek[STAGE2_BLK_CNT_MAX];
+    uint8_t unused[64];
+} __attribute__ ((packed)) EckdStage1b;
+
+typedef struct EckdStage1 {
+    uint8_t reserved[72];
+    struct EckdSeekArg seek[2];
+} __attribute__ ((packed)) EckdStage1;
+
+typedef struct EckdCdlIpl2 {
+    uint8_t key[4]; /* == "IPL2" */
+    struct EckdStage1 stage1;
+    XEckdMbr mbr;
+    uint8_t reserved[24];
+} __attribute__((packed)) EckdCdlIpl2;
+
+typedef struct EckdLdlIpl1 {
+    uint8_t reserved[24];
+    struct EckdStage1 stage1;
+    BootInfo bip; /* BootInfo is MBR for LDL */
+} __attribute__((packed)) EckdLdlIpl1;
 
 typedef struct IplVolumeLabel {
     unsigned char key[4]; /* == "VOL1" */