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Re: [qemu-s390x] [PATCH v5 15/15] s390-bios: Support booting from real d
Jason J. Herne
Re: [qemu-s390x] [PATCH v5 15/15] s390-bios: Support booting from real dasd device
Mon, 1 Apr 2019 11:35:56 -0400
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On 3/29/19 4:33 AM, Thomas Huth wrote:
On 13/03/2019 17.31, Jason J. Herne wrote:
Will fix this, and the other typos you've pointed out.
+static char prefix_page[PAGE_SIZE * 2]
+ __attribute__((__aligned__(PAGE_SIZE * 2)));
+static void enable_prefixing(void)
+ memcpy(&prefix_page, (void *)0, 4096);
You could use the "lowcore" variable from s390-arch.h here instead of
"(void *)0", I guess.
+static void disable_prefixing(void)
+ /* Copy io interrupt info back to low core */
+ memcpy((void *)0xB8, prefix_page + 0xB8, 12);
Maybe use &lowcore->subchannel_id instead of 0xB8 ? ... not sure whether
that's nicer here, though...
I think it is nicer using the named field. I Will make that change.
Note: We need to keep the (void*) cast to prevent a compiler warning about discarding
+static void ipl1_fixup(void)
+ Ccw0 *ccwSeek = (Ccw0 *) 0x08;
+ Ccw0 *ccwSearchID = (Ccw0 *) 0x10;
+ Ccw0 *ccwSearchTic = (Ccw0 *) 0x18;
+ Ccw0 *ccwRead = (Ccw0 *) 0x20;
+ CcwSeekData *seekData = (CcwSeekData *) 0x30;
+ CcwSearchIdData *searchData = (CcwSearchIdData *) 0x38;
+ /* move IPL1 CCWs to make room for CCWs needed to locate record 2 */
+ memcpy(ccwRead, (void *)0x08, 16);
All the other CCWs in this section still need to use the numeric memory references. I
think it makes it slightly more confusing to switch just the one to using the struct. For
this reason I prefer it the way it is, if you're okay with that.
+static void lpsw(void *psw_addr)
+ PSWLegacy *pswl = (PSWLegacy *) psw_addr;
+ pswl->mask |= PSW_MASK_EAMODE; /* Force z-mode */
+ pswl->addr |= PSW_MASK_BAMODE;
+ asm volatile(" llgtr 0,0\n llgtr 1,1\n" /* Some OS's expect to be */
+ " llgtr 2,2\n llgtr 3,3\n" /* in 32-bit mode. Clear */
+ " llgtr 4,4\n llgtr 5,5\n" /* high part of regs to */
+ " llgtr 6,6\n llgtr 7,7\n" /* avoid messing up */
+ " llgtr 8,8\n llgtr 9,9\n" /* instructions that work */
+ " llgtr 10,10\n llgtr 11,11\n" /* in both addressing */
+ " llgtr 12,12\n llgtr 13,13\n" /* modes, like servc. */
+ " llgtr 14,14\n llgtr 15,15\n"
+ " lpsw %0\n"
+ : : "Q" (*pswl) : "cc");
Have you tried to use jump_to_low_kernel() already? ... it might be
cleaner to do the diag 0x308 reset here, too, to avoid that some part of
the machine is in an unexpected state...
I had not tried jump_to_low_kernel() until just now. It *does* seem to work... and
eliminates the need for the manual register clearing. I assume the diag 308 reset baked
into the jump_to_low_kernel() is responsible for that? I guess switching to
jump_to_low_kernel() would be a good thing ... I'll admit I'm slightly uneasy about it
since I've been testing my way for so long :) But jump_to_low_kernel() works for all of my
manual test cases.
-- Jason J. Herne (address@hidden)
- Re: [qemu-s390x] [PATCH v5 15/15] s390-bios: Support booting from real dasd device,
Jason J. Herne <=