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Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary
From: |
Marcelo Tosatti |
Subject: |
Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary |
Date: |
Fri, 25 Oct 2013 02:58:05 -0200 |
User-agent: |
Mutt/1.5.21 (2010-09-15) |
On Fri, Oct 25, 2013 at 12:55:36AM +0100, Paolo Bonzini wrote:
> > + if (hpagesize == (1<<30)) {
> > + unsigned long holesize = 0x100000000ULL - below_4g_mem_size;
> > +
> > + memory_region_init_alias(ram_above_4g, NULL, "ram-above-4g",
> > ram,
> > + 0x100000000ULL,
> > + above_4g_mem_size - holesize);
> > + memory_region_add_subregion(system_memory, 0x100000000ULL,
> > + ram_above_4g);
> > +
> > + ram_above_4g_piecetwo =
> > g_malloc(sizeof(*ram_above_4g_piecetwo));
> > + memory_region_init_alias(ram_above_4g_piecetwo, NULL,
> > + "ram-above-4g-piecetwo", ram,
> > + 0x100000000ULL - holesize, holesize);
> > + memory_region_add_subregion(system_memory,
> > + 0x100000000ULL +
> > + above_4g_mem_size - holesize,
> > + ram_above_4g_piecetwo);
>
> Why break it in two? You can just allocate extra holesize bytes in the
> "ram" MemoryRegion, and not map the part that corresponds to
> [0x100000000ULL - holesize, 0x100000000ULL).
- If the "ram" MemoryRegion is backed with 1GB hugepages, you might not
want to allocate extra holesize bytes (which might require an entire
1GB page).
- 1GB backed RAM can be mapped with 2MB pages.
> Also, as Peter said this cannot depend on host considerations. Just do
> it unconditionally, but only for new machine types (pc-1.8 and q35-1.8,
> since unfortunately we're too close to hard freeze).
Why the description of memory subregions and aliases are part of machine
types?
- [Qemu-devel] [patch 0/2] align >4GB guest RAM to a 1GB boundary, in case of 1GB-sized hugetlbfs, Marcelo Tosatti, 2013/10/24
- [Qemu-devel] [patch 1/2] exec: add qemu_get_ram_hpagesize, Marcelo Tosatti, 2013/10/24
- [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/24
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Peter Maydell, 2013/10/24
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Paolo Bonzini, 2013/10/24
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary,
Marcelo Tosatti <=
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Paolo Bonzini, 2013/10/25
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/25
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Paolo Bonzini, 2013/10/25
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Gerd Hoffmann, 2013/10/30
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Paolo Bonzini, 2013/10/30
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, igor Mammedov, 2013/10/25
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/25
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, igor Mammedov, 2013/10/27
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/28
- Re: [Qemu-devel] [patch 2/2] i386: pc: align gpa<->hpa on 1GB boundary, Marcelo Tosatti, 2013/10/28