RISC-V: use physmem to manage physical memory

[mhorne]

Summary

Replace our hand-rolled functions with the generic ones provided by
kern/subr_physmem.c. This greatly simplifies the initialization of
physical memory regions and kernel globals.

[kp]

I've found this to fail to boot, because it didn't reserve memory for the DTB (supplied by BBL). I'm not entirely sure if that's a result of an issue with your patch, or if there's something wrong in our local tree.

How is the DTB memory supposed to be reserved?

The following fixes the immediate problem for me:

@@ -806,9 +808,11 @@ initriscv(struct riscv_bootparams *rvbp)
 #ifdef FDT
        try_load_dtb(kmdp, rvbp->dtbp_virt);
 #endif
+       /* Reserve memory for the DTB. */
+       physmem_exclude_region(rvbp->dtbp_phys, L2_SIZE, EXFLAG_NOALLOC);

[mhorne]

In D24154#532404, @kp wrote:

I've found this to fail to boot, because it didn't reserve memory for the DTB (supplied by BBL). I'm not entirely sure if that's a result of an issue with your patch, or if there's something wrong in our local tree.

How is the DTB memory supposed to be reserved?

The following fixes the immediate problem for me:

@@ -806,9 +808,11 @@ initriscv(struct riscv_bootparams *rvbp)
 #ifdef FDT
        try_load_dtb(kmdp, rvbp->dtbp_virt);
 #endif
+       /* Reserve memory for the DTB. */
+       physmem_exclude_region(rvbp->dtbp_phys, L2_SIZE, EXFLAG_NOALLOC);

Looks like I missed linking one of the parents. This patch also depends on D24152.

[mhorne]

Rebase.

[kp]

In D24154#532415, @mhorne wrote:

Looks like I missed linking one of the parents. This patch also depends on D24152.

Thanks! I should have realised. I'd already seen the other patch, but somehow neglected to include it in my tests.

[br]

sys/riscv/riscv/machdep.c

858 ↗

(On Diff #69943)

Do you prefer to use square brackets for a single line statements?

[mhorne]

Rebase

[mhorne]

Ping. Any opposition to this one? I would like to commit the set of patches soon.

[nick]

These changes look good. I can confirm that this works.

[mhorne]

Keep physmap globals in machdep.c.