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70 lines
2.6 KiB
Text
70 lines
2.6 KiB
Text
From: 3n4ch3@gmail.com (Enache Adrian)
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Subject: [Qemu-devel] [kqemu patch] get Open/NetBSD to work with the kqemu
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accelerator
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Date: Mon, 5 Nov 2007 22:00:12 +0200
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Message-ID: <281a8e2bec2c45bce8b89bf96457995c.fa6dd951@aerenchyma>
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To: qemu-devel@nongnu.org
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[sorry if this is the wrong list, but I haven't figured out any public
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address where I could send kqemu bug reports and patches]
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Currently, both NetBSD and OpenBSD are hanging or crashing when running
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on qemu with the kqemu accelerator enabled.
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This happens because both systems are using a weird scheme where they
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are loading the GDT table with LGDT up-front (with the limit set to
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the maximum), but are growing the table and actually mapping the memory
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behind it only when needed.
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(see src/sys/arch/i386/i386/gdt.c in both source trees)
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That is causing the kqemu accelerator to generate a page fault in
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update_dt_cache() when trying to fill its 'soft' tlb with pages that
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are beyond the real end of the GDT table.
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With this diff applied, NetBSD and OpenBSD seem to run fine with
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kqemu + user-only virtualization (I've tried netbsd-4.0-rc2 and
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openbsd 4.2).
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Full virtualization (-kernel-kqemu) doesn't work yet for different
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reasons (I think).
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Regards,
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Adi
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Index: common/monitor.c
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--- common/monitor.c Tue Feb 6 23:02:00 2007
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+++ common/monitor.c Mon Nov 5 18:59:58 2007
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@@ -990,7 +990,8 @@ static void *map_vaddr(struct kqemu_state *s, unsigned
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e = &s->soft_tlb[(addr >> PAGE_SHIFT) & (SOFT_TLB_SIZE - 1)];
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redo:
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if (e->vaddr[(is_user << 1) + is_write] != (addr & PAGE_MASK)) {
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- soft_tlb_fill(s, addr, is_write, is_user);
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+ if(cpu_x86_handle_mmu_fault(s, addr, is_write, is_user, 1))
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+ return NULL;
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goto redo;
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} else {
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taddr = e->addend + addr;
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@@ -1802,6 +1803,11 @@ static void update_dt_cache(struct kqemu_state *s, int
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page_end = dt_end;
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sel2 = sel + (page_end - dt_ptr);
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ptr = map_vaddr(s, dt_ptr, 0, 0);
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+ if(!ptr)
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+ /* Open/NetBSD have a 'dynamic' GDT, but they load the gdt
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+ register with LGDT only once and with a limit far beyond
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+ the end of the memory actually mapped for the table */
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+ goto skip_the_rest;
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ram_addr = ram_ptr_to_ram_addr(s, ptr);
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if (dt_changed ||
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s->dt_ram_addr[dt_type][pindex] != ram_addr ||
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@@ -1818,7 +1824,7 @@ static void update_dt_cache(struct kqemu_state *s, int
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sel_end = (s->dt_limit[dt_type] + 1) & ~7;
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if (sel < sel_end)
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reset_dt_entries(s, dt_type, sel, sel_end);
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-
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+skip_the_rest:
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s->dt_base[dt_type] = base;
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s->dt_limit[dt_type] = limit;
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}
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